Continuous Cylinder Research Articles

Acquiring reliable hydrogen crossover data of hydrated ion exchange membranes to elucidate the ion conducting channel morphology

The morphology of ion channels within ion exchange membranes (IEM) has long been disputed by researchers. Several accepted models include the Gierke’s discrete spherical cluster model, continuous parallel cylinder model, and flat-layered model. The primary experimental data to support each model were mostly small-angle X-ray spectroscopy (SAXS). In this work, we propose that hydrogen permeability (i.e. crossover) data of hydrated IEMs could provide valuable insights into understanding the ion channel connectivity and continuity within the membrane. We re-derived the two-phase Maxwell-Eucken transport models to predict the hydrogen crossover of hydrated IEMs. The model accurately predicted the hydrogen crossover of Nafion and in-house BPSH membrane series within 10% error range. The predicted results were experimentally validated using the pressure decay method (PDM) developed in our group specifically for this purpose. By comparing the degree of change in hydrogen crossover between the dry and hydrated membranes, it was possible to extract semi-qualitative information about the membrane’s controversial ion-conducting channel morphology. Interestingly, our experimental data and model prediction corroborates with the Gierke’s conjecture that the water phase within the ion channel exists as discrete spherical clusters, not as the continuous percolated phase (the parallel cylinder model). Although there is yet no consensus on the internal morphology of ion channels, our work suggests that hydrogen crossover data can be useful in elucidating the ion channel morphology.

Heat transfer phenomenon in a retarded boundary layer over a moving continuous cylinder

The phenomena of flow separation on a surface of finite length is analogous to boundary layer flows caused by retarded motion of continuous surfaces, which ultimately seize at some downstream position and increase drag on aerodynamic vehicles. According to the literature, a stationary surface of finite length will generate a boundary layer that is less energetic than one that is developed over a moving continuous surface. This means that a moving continuous surface is preferred to a stationary surface of finite length for the sustainability of the transport phenomena in such a retarded flow, which must eventually meet the flow separation. Therefore, the goal of this study is to conduct a heat transfer analysis in a delayed laminar boundary layer generated by a moving continuous cylinder with a constant radius. Wall temperature of uniform nature is considered in this investigation. In most of the boundary layer flows the self-similarity of the flow does not persist because of choosing the reference velocity of the desired character. Thus, the problem becomes non-similar. In general, the non-similarity of a flow may appear due to various aspects of the problem such as the retarded nature of the reference velocity, the surface temperature, the curvature of the body, etc. Surface transverse curvature imparts favorable consequences on the separating boundary layer and hence on the seizing flow character. The purpose of this investigation is to determine how TVC and the wall velocity power index affect temperature profiles, the local Nusselt number , the thickness of the thermal layer, and the thermal diffusivity of heat in a retarded boundary layer. In addition to this, the influence of Prandtl number and Stanton number has also been investigated. The numerical solution is computed using an implicit finite difference scheme, commonly known as the Keller-Box scheme in MATLAB scientific computing software Investigations reveal that the TVC assists the thermal transport by enhancing the rate of heat transfer and the length of the convectively heat transferring region (starting from the leading edge to the location where the flow gets seized) by increasing the longitudinal region of flow (starting from the leading edge to the location where the flow gets seized) on the surface. The surface wall velocity power index acts to decrease the temperature distribution and reduces the heat transfer rate at the surface. Further, the Prandtl number reduces the thermal boundary layer thickness and the Stanton number but enhances the local Nusselt number.

PEMBELAJARAN KONTROL SISTEM PNEUMATIK SEBAGAI PENUNJANG KOMPETENSI SISTEM HIDROLIK DAN PNEUMATIK DI SMK NEGERI 1 ADIWERNA

Community Service Activities carried out are providing understanding and thinking patterns about pneumatic systems control that work electro-pneumatically to students of SMK Negeri 1 Adiwerna grade XII majoring in Technical Light Vehicle (TLV). Knowledge of pneumatic systems is one of the competencies that are usually difficult to understand by TLV students. Whereas pneumatic systems have many applications in the industrial world. By using a facility in the form of an Electro-Pneumatic Trainer, the delivery of discussions about pneumatic system control will be more easily understood by students. By referring to the wiring diagram, students are explained to be able to read and understand the intent and working process of the pneumatic systems control and put it into practice immediately. There are 3 types of pneumatic systems control delivered, (1) single-cylinder pneumatic control systems, (2) single-cycle multiple cylinder pneumatic control systems, (3) continuous cycle multiple cylinder pneumatic control systems. Students are very enthusiastic about receiving explanations and practicing all three control systems.

Application of Vortex Induced Vibration Systems to Improve Vertical Mixing and Create Light/Dark Cycles for Enhanced Algal Biomass Productivity in Raceway Ponds

Limited light availability due to insufficient vertical mixing is one of the main drawbacks of raceway ponds (RWPs), the most common type of microalgae cultivation system. In this study, we have investigated the application of vortex induced vibration (VIV) systems to improve vertical mixing in order to enhance algal biomass productivity. The system consists of a cylinder submerged parallel to the bottom in the pond with two springs attached at its ends. The cylinder oscillates perpendicularly to the flow direction at the pond to increase vertical mixing. A VIV system, which requires no additional energy input, was installed in a 0.3 m deep raceway pond and continuous cylinder oscillation was successfully achieved. Cylinder oscillation frequency of 1.24 s−1 and amplitude of 6.5 cm have been obtained experimentally for 0.3 m s−1 flow velocity. Numerical simulations were carried out with experimental parameters using CFD code and were in good accordance with experimental results. Numerical analysis revealed that it is possible to create high frequency light/dark cycles; mean light/dark cycle frequencies were found to be 2.33 s−1, 5.28 s−1 and 21.17 s−1, at lowermost, middle and uppermost cylinder positions, respectively. Enhanced velocity magnitude of 0.3 m s−1 was achieved in the vertical direction; vertical motion of flow resulting from cylinder oscillation covers about two thirds of pond depth. Effectiveness of the VIV system on biomass growth was also verified by comparative Chlorella vulgaris cultivation under outdoor conditions. It has been observed that the VIV system installed reactor enhanced biomass production capacity by over 20% compared to the control pond. These results indicate that the presented method possesses a potential for enhanced algal biomass production without significant increase in installation and operating costs.

Intrusive growth of initials does not affect cambial circumference in Robinia pseudoacacia.

This study aimed to test the hypothesis whether intrusive growth of initial cells is related to the increase in circumference of Robinia pseudoacacia vascular cambium—both qualitatively and quantitatively. The mode of intrusive growth of cambial initial cells was also studied. Samples collected from tree trunks were examined using series of semi-thin transverse sections. Anatomical reconstructions of radial and tangential planes of analysed fragments of cambial tissue were made. Observations and measurements have shown that the intrusive growth of R. pseudoacacia initial cells does not contribute to an increase in tangential dimension of observed tissue fragments where cell rearrangement occurs. Moreover, initially separated tangential walls of cells (between which cambial initial cell elongates intrusively) are transformed into obliquely oriented walls. These results stand in accordance with a statement that only symplastic growth of initials, not intrusive growth, is responsible for the increase in circumference in all woody plants with the continuous cambial cylinder. Moreover, we managed to capture the moment of transition of initial status from one cell to another for the first time. This phenomenon may be explained on the basis of the system of mechanical stresses operating not only in the secondary meristematic tissue but also in a whole plant organism.

Wake behind a discontinuous cylinder: unveiling the role of the large scales in wake growth and entrainment

The turbulent flow in the wake of a discontinuous cylinder (DC) was investigated. The DC geometry consisted of cylinder segments $5D$ long (with $D$ being the diameter of the cylinder) separated by gaps of width $2.5D$ . Particle image velocimetry and hot-wire anemometry were used to analyse the flow at two Reynolds numbers, $Re = 4000$ and $10\,000$ , for $x/D \le 180$ . Large eddy simulations for both the DC and the infinite continuous cylinder (CC) wakes were also carried out at $Re = 10\,000$ . The DC configuration was devised to trigger the shedding of horseshoe vortices (HSV) in the very-near-wake region with the intent of illustrating the role that these three-dimensional HSVs, previously identified in the far-wake region of CC, play in the entrainment process in turbulent wakes. The DC geometry produced HSVs by the interaction between the high momentum flow through the gaps and the main spanwise vortex shed behind each cylinder segment, while in the CC wake they evolve from near-wake instabilities straddled with hairpin vortices that detach spanwise vorticity from the shed Kármán vortices. The DC wake was found to grow and spread in the transverse direction with a much faster rate than for the CC wake, up until approximately $x/D \approx 50$ . Prior to this location, the enhanced growth rate caused by the shear-aligned HSV led to a wake width of approximately 3 times that of the CC wake, with a maximum mean velocity deficit that was approximately half.

Stem and Leaf Anatomy of Aragoa (Plantaginaceae): In Search of Lost Rays.

Aragoa is a shrubby genus endemic to páramo in the northern Andes representing the sister group to Plantago and Limosella. Stem and leaf structure of Aragoa corrugatifolia were studied to clarify the evolutionary pathways and ecological significance of their anatomical traits. Aragoa and Plantago share a non-fascicular primary vascular system, rayless wood and secondary phloem, and anomocytic stomata. Aragoa is distinctive from most Plantaginaceae in the presence of cortical aerenchyma and of helical thickenings in vessels. Its procambium emerges in the primary meristem ring as a continuous cylinder. The view on the ring meristem and procambial strands as developmental stages in the formation of a primary vascular system is not relevant for Aragoa, and probably for other Plantaginaceae. The raylessness is synapomorphic for the crown clade of Plantaginaceae comprising Aragoa, Littorella, Plantago, Veronica, Picrorhiza, Wulfenia, and Veronicastrum. The loss of rays is thought to be predetermined by procambium rather than by the vascular cambium. The extremely narrow vessels with helical thickenings are presumably adaptive to hydric and thermic conditions of páramo. Cortical aerenchyma is thought to be a response to the local hypoxia caused by the water retained by ericoid leaves. Trichomes on juvenile leaves are expected to be the traits of considerable taxonomic importance.

Development of pharmacognostic parameters for the leaf of Bridelia scandens (Roxb.) Willd

Background: Pharmacognostic study of medicinal plants is an important parameter for standardization and authentication of plants, with the help of which adulteration and substitution can be prevented. The present study deals with pharmacognostic profile of leaf of Bridelia scandens (Roxb).Willd. an important traditional plant, belonging to family Euphorbiaceae used to treat various ailments. Methods: The present study includes macroscopic and microscopic studies, quantitative microscopy, and physiochemical characters such as ash value, extractive values, fluorescence analysis, and total phenol and flavonoid content. Results: Macroscopically, the leaves are B. scandens are elliptic –oblong or obavate, dark green above, pale green below lateral veins. Microscopically, leaf consists of thick semicircular midrib and the lamina, cortical zone ending with thick continuous cylinder of sclerenchyma cells. Sclerenchyma cylinder completely enclosed the vascular cylinder of the midrib, consists of only continuous thick layer of phloem. Xylem cylinder consists of numerous short or long radial chains of vessels. The lateral vein is flat on the adaxial side and prominently projecting hemispherical body on the adaxial side. Powder microscopy of leaf revealed the presence of spiral xylem vessels, rosette and prismatic calcium oxalate crystals and trichomes. A Physiochemical characteristic was also determined. Conclusion: Existing literature revealed that so far, no Pharmacognostic study has been reported on the leaf of B. scandens. Findings from this investigation can be used for its identification and determination of quality and purity of medicinally important plant. Thus exploring the usefulness of pharmacognostic evaluation to validate and authenticate drug.

Vincetoxicum indicum (Burm.f.) Mabb. - a case of transient abnormal secondary thickening in stem

Vincetoxicum indicum (Burm.f.) Mabb. (Syn. Tylophora indica (Burm.f.) Merr., T. asthmatica W. &A.), an important twining medicinal plant of India, was found to show a transient anomalous secondary thickening to facilitate the twisting of stem around a support. The very young stem had a continuous primary xylem cylinder, the protoxylem of which differentiated to two large bundles on the opposing sides and many smaller bundles in between. In the initial stages of maturation, the cambium outside the two large protoxylem groups behaved abnormally in producing more phloem outwards and little or no secondary xylem inwards to produce two wedge shaped phloem groups on opposite sides. The production of crescent shaped secondary xylem on the other two sides which fell at a right-angled plane resulted in bulging of these sides away from the anomalous cambium to create a rectangular stem having two broad sides which were used as the facing sides of stem against a support. As soon as the twisting nature was established, the anomaly was reversed and the anomalous cambial patches started behaving normally to produce a complete ring of secondary xylem. As this abnormal behaviour happened only during the twisting of stem, this is considered as an adaptational anomalous secondary thickening.

MATHEMATICAL MODELING OF THE HEAT TRANSFER PROCESS IN THE SYSTEM OF MULTILAYER CYLINDRICAL SOLID BODIES CONSIDERING INTERNAL SOURCES OF HEAT

The article is devoted to the application of the direct method to the study of heat transfer processes in the "continuous cylinder inside a multilayer cylindrical shell" system. To solve the initial problem, an auxiliary problem is posed with a “remote” cylinder of sufficiently small radius. The solution is based on the reduction method, the concept of quasiderivatives, the Fourier scheme using the modified eigenfunctions method. The solution to the original problem was obtained by following the radius of the remote cylinder to zero.

ANALYZING TVC EFFECTS ON SEIZING FLOW DUE TO RETARDED MOTION OF A CONTINUOUS CYLINDER

ANALYZING TVC EFFECTS ON SEIZING FLOW DUE TO RETARDED MOTION OF A CONTINUOUS CYLINDER

INFLUENCE OF IMPERFECT THERMAL CONTACT ON HEAT EXCHANGE IN THE SYSTEM OF MULTILAYER CYLINDRICAL BODIES

Introduction. Solving the problem of heat transfer in multilayer structures devoted a large number of works. The vast majority of them are limited to the case of perfect thermal contact between the layers. However, according to the authors, the problems of thermal conductivity in multilayer structures using into account the imperfect thermal contact are insufficiently studied. The number of such studies is quite limited. Also, known studies are usually limited to two layers. That is because the increase in the number of layers (given the choice of methods of practical implementation) leads to several computational difficulties. Therefore, the problem of constructing an effective analytical scheme for the study of heat transfer processes in multilayer structures in the presence of imperfect thermal contact between the layers remains an urgent task.Purpose. Application of the direct method to the study of heat transfer processes in the system "continuous cylinder inside a multilayer cylindrical shell" with imperfect thermal contact.Methods. An auxiliary problem set for the distribution of the temperature field in a multilayer solid cylindrical hollow body (a cylinder of the sufficiently small radius is "removed") taking into account the imperfect thermal contact between the individual layers. According to the already known scheme of the direct method solve this problem.Results. Boundary transition obtained the solution of the original problem. Boundary transition: the radius of the"removed" cylinder, with the centre at the origin, goes to zero. This approach established that the solution to the problemis limited in the whole structure. In this case, the solution obtained explicit formulas.Conclusions. Effective analytical scheme constructed for application of the direct method to the study of heattransfer processes in multilayer hard cylindrical solids taking into account the non-ideal thermal contact between thelayers. The number of layers, their size and arrangement are considered arbitrary.

Imperfection-insensitive continuous tow-sheared cylinders

The design of thin-walled cylinders in axial compression is limited by sensitivity to geometric imperfections. This paper focuses on reducing this imperfection sensitivity from a design perspective. By using variable-angle composites, the load paths are tailored to reduce the effective area over which imperfections can initiate buckling. Continuous Tow Shearing (CTS) is one such variable-angle manufacturing technique. It does not cause manufacturing defects associated with Automated Fibre Placement and entails a fibre angle-thickness coupling that results in a local thickness build-up—used as a design feature to embed stiffeners in the cylinder. Nonlinear finite element models with seeded imperfections are used to calculate knockdown factors (KDF). It was found that there is an inverse trend between embedded stiffener frequency and the KDF. The best performing CTS cylinder has a KDF 30% greater and a specific buckling load 4% greater than a QI cylinder, the optimal straight-fibre laminate for axial cylinder buckling. It was also found that, the smaller the effect of geometric imperfections on the pre-buckling strain field, the greater the KDF of the cylinder. This novel finding shows that a computationally inexpensive nonlinear analysis can provide a first-order approximation of the imperfection sensitivity of a cylinder in axial compression.

РЕАЛЬНИЙ ВАРІАНТ ОДНОВИМІРНОЇ ЗАДАЧІ ТЕПЛОПРОВІДНОСТІ ДЛЯ СУЦІЛЬНОГО НЕОБМЕЖЕНОГО СТАЛЕВОГО ЦИЛІНДРА

Сучасний етап розвитку методів проведення наукових досліджень характеризується широким використанням засобів обчислювальної техніки та чисельного моделювання. Ці потужні обчислювальні засоби суттєво збільшують можливості нової методології наукових досліджень, а саме, встановлюють більш тісну взаємодію експериментальних та теоретичних досліджень. В умовах промислового виробництва особливо велике значення має скорочення матеріальних та часових ресурсів при розробці нових технологій та освоєнні нового сортаменту продукції та нових сталей. Для термічної обробки металовиробів ці питання можна вирішити за допомогою сучасних методів моделювання та розрахунків, які при мінімальних витратах часу та матеріальних засобів дозволяють досліджувати різні технологічні процеси, проводити їх розробку та оптимізацію для різних матеріалів з отриманням конкретних рішень.

Extension of a Piecewise Uniform Composite Rod

An exact analytical solution is obtained for the extension problem in the case of an infinitely long continuous round cylinder attached to an external hollow round cylinder. This mechanical system is considered as a composite rod whose components are made of elastic materials with different mechanical characteristics. The method of solving this problem is based on the approach proposed by the author of this paper to solve the plane stress state problem in a spatial formulation, which allows one to integrate the equilibrium equations in finite form. The distribution of displacements and stresses in the rod is discussed.

A New Unified Solution for Circular Opening considering Different Strength Criteria and the Postpeak Elastic Strain Form

The strength criterion is an extremely important basis for evaluating the stability of surrounding rock and optimizing the support pressure design. In this paper, nine different strength criteria are summarized and simplified based on the reasonable assumption. Then, a new unified criterion equation is established, which includes all strength theories proposed by this paper. Meanwhile, a new unified closed‐form solution for circular opening based on the newly proposed unified criterion equation is deduced with the infinite and finite external boundary combining with the nonassociative flow rule under plane strain conditions. In the plastic zone, four different elastic strain assumptions are applied to solving the plastic zone deformation considering the effect of rock mass damage. The solution’s validity is also verified by comparison with the traditional solution. Finally, the influences of strength criteria, dilation coefficient, elastic strain form of plastic zone, and rock mass damage on the mechanical response of surrounding rock are discussed in detail. The research result shows that TR and VM criteria give the largest plastic zone radius, followed by IDP, MC, and MDP criteria, and seem to underestimate the self‐strength of rock mass; The CDP criterion gives the smallest plastic zone radius and may overestimate the self‐strength of rock mass; UST0.5, GSMP, GMC, and GLD criteria that reasonably consider the effect of internal principal stresses give an intermediate range and can be strongly recommended for evaluating the mechanics and deformation behavior of surrounding rock; as the dilation coefficient gradually increases, the dimensionless surface displacement presents the nonlinear increase characteristics; the deformation of plastic zone and the ground response curve, which are closely related to the strength criteria, are also greatly influenced by the elastic strain assumption in the plastic zone and rock mass damage degree. The assumption that the elastic strain satisfies Hook’s law (Case 3) may be more reasonable compared with the continuous elastic strain (Case 1) and thick‐walled cylinders (Case 2) assumptions; in addition, the Young’s modulus power function damage model seems to give more reasonable solution for the deformation of plastic zone and is suggested to be a preferred method for solving plastic displacement. The research results can provide very important theoretical bases for evaluating the tunnel stability and support design reliability of different lithology rock masses in underground engineering.

МОДЕЛИРОВАНИЕ НЕСТАЦИОНАРНЫХ СВЯЗАННЫХ МЕХАНОДИФФУЗИОННЫХ ПРОЦЕССОВ В ИЗОТРОПНОМ СПЛОШНОМ ЦИЛИНДРЕ

We considered the one-dimensional polar-symmetric problem of stress-strain state determining of a continuum isotropic multicomponent cylinder. The cylinder is affected by unsteady surface elastic diffusive perturbations. The coupled system of elastic diffusion equations in the polar coordinate system is used as a mathematical model. The problem solution is sought in the integral form and is represented as convolutions of Green's functions with functions defining surface elastodiffusive perturbations. Mechanical loads and diffusion fields are considered as external influences. We used the Laplace transform by time, and Fourier series expansion in first kind Bessel functions to find the Green's functions. To calculate the coefficients of these series, we obtained formulas for transforming differential operators of the first, second, and third orders using the Hankel integral transform on a segment, which allowed us to reduce the initial boundary-value problem of mechanodiffusion to a system of linear algebraic equations. Laplace transforms of Green's functions are represented through rational functions of the Laplace transform parameter. The Laplace transform inversion is done analytically due to residues and operational calculus tables. As a result, Analytical expressions of surface Green's functions are obtained for the considering problem. Numerical study of the mechanical and diffusion fields interaction in a continuous isotropic cylinder is performed. We used two-component material as an example. The cylinder is under pressure uniformly distributed over the surface. The solution is presented in analytical form and in the form of three-dimensional graphs of the desired displacement fields and concentration increments as functions of time and radial coordinate. This calculation example allows us to demonstrate the coupling effect of mechanical and diffusion fields. It manifests itself as a change in the concentrations of the continuum components under the influence of external unsteady surface pressure.

Stiff Composite Cylinders for Extremely Expandable Structures

The realization of concurrently largely expandable and selectively rigid structures poses a fundamental challenge in modern engineering and materials research. Radially expanding structures in particular are known to require a high degree of deformability to achieve considerable dimension change, which restrains achievable stiffness in the direction of expanding motion. Mechanically hinged or plastically deformable wire-mesh structures and pressurized soft materials are known to achieve large expansion ratios, however often lack stiffness and require complex actuation. Cardiovascular or drug delivery implants are one example which can benefit from a largely expandable architecture that is simple in geometry and intrinsically stiff. Continuous shell cylinders offer a solution with these properties. However, no designs exist that achieve large expansion ratios in such shells when utilizing materials which can provide considerable stiffness. We introduce a new design paradigm for expanding continuous shells that overcomes intrinsic limitations such as poor deformability, insufficient stiffness and brittle behaviour by exploiting purely elastic deformation for self-expandable and ultra-thin polymer composite cylinders. By utilizing shell-foldability coupled with exploitation of elastic instabilities, we create continuous cylinders that can change their diameter by more than 2.5 times, which are stiff enough to stretch a confining vessel with their elastic energy. Based on folding experiments and analytical models we predict feasible radial expansion ratios, currently unmatched by comparable cylindrical structures. To emphasize the potential as a future concept for novel simple and durable expanding implants, we demonstrate the functionality on a to-scale prototype in packaging and expansion and predict feasible constellations of deployment environments.

DESIGN AND DEVELOPMENT OF OXYGEN MONITORING WITH GALVANIC OXYGEN SENSOR BASED ON MICROCONTROLLER ARDUINO UNO

The Oxygen Analyzer is a tool for measuring the oxygen content in a gas exhaust system. The Oxygen analyzer is used in various fields including the fields of industry and health. In the health sector, the Oxygen Analyzer is used to measure oxygen content in Continuous Positive Airway Pressure (CPAP), anesthetic machines, ventilator machines, or oxygen cylinders. In this study the researchers made an Oxygen Analyzer that can read oxygen levels 21% 100% with a reading range per digit. This study uses an oxygen sensor that serves to detect oxygen levels which is set with an Arduino Uno microcontroller. The testing is carried out directly on a ventilator as a comparison tool. The method of data analysis in this study uses descriptive analysis. In this study the tool created was able to detect the value of oxygen levels in the range of 21% - 100% with an average error of 0.01%.

English

The aim of this work was to determine the anatomical adaptations of leaves and stems of four species of Poaceae (Cynodon dactylon L. Pers., Chloris barbata SW. (Chloridoideae), Setaria verticillata L. P. Beauv., and Panicum coloratum L. (Panicoideae)) growing naturally at Al-Ha'ir region near Riyadh, Saudi Arabia. Cross-sections of the leaves revealed that the epidermis cells were spherical to oval and formed one layer with a thick cuticle as well as numerous bulliform cells in a fan shape and prickles. Ground tissue (mesophyll) consists mostly of chlorenchyma cells. A large vascular bundle surrounded by two bundle sheaths, outer sheath parenchyma and inner sheath sclerenchyma were observed in C. barbata and C. dactylon, while one bundle sheath of sclerenchyma surrounds the vascular bundle in S. verticillata and P. coloratum, while one bundle sheath with chlorenchymatous cells surrounded the small vascular bundles. Our results showed that all species contained a Kranz anatomy indicative of a C4 photosynthetic pathway despite belonging to two different subfamilies, Panicoideae and Chloridoideae. Oil droplets appeared in the mesophyll tissue of P. coloratum and S. verticillata. Cross-sections of stems revealed an epidermis which consists of one layer of cells with spherical to oval shape and had a thick cuticle. Ground tissue contains strands of chlorenchyma cells followed by sclerenchyma tissue surrounding vascular bundles, thereby making a continuous cylinder. The vascular bundles were scattered in the ground tissue, with each vascular bundle surrounded by a single sclerenchymatous bundle sheath. Our results indicate that these plants were characterized by anatomical adaptations that enhance drought-tolerance capabilities, facilitating survival in arid and semi-arid regions such as Al-Ha'ir and thus these plants can be used to increase vegetation cover and pasture area in dry environments.   Key words: Anatomy, adaptations, Poaceae, Cynodon dactylon, Chloris barbata, Setaria verticillata, Panicum coloratum.