Unit Element Research Articles

Development of two port multilayer MIMO fractal antenna for multiband applications

Abstract A Two Port Multilayer Multi Input Multi Output Fractal Antenna (TPMMIMOFA) for Multiband Applications is proposed in this paper. It comprised of two Koch Fractal Unit Element Antenna (KFUEA). HFSS is used to design and analyze proposed TPMMIMOFA. Proposed TPMMIMOFA has been designed on FR4 substrate having a size of 60 × 59.8 × 1.6 mm3. Later on, two layers of FR4 material as superstrate of size of 45 × 59.8 × 1 mm3 are used to improve antenna’s bandwidth and gain. Proposed TPMMIMOFA is fabricated and tested in lab for the validation of its performance. Proposed TPMMIMOFA resonates at 2.85 (2.66–3.82 GHz), 4.75 (4.57–4.91 GHz), 6.3 (6.06–6.50 GHz), 7.81 GHz (7.53–8.08 GHz) and it has a fractional bandwidth of 40.7%, 7.16%, 6.98% and 7.04%. The proposed TPMMIMOFA exhibits excellent performance in terms of Envelope Correlation Coefficient (ECC) < 0.4, Mean Effective Gain (MEG) < 3 dB, Diversity Gain (DG) > 9.8, Total Active Refection Coefficient (TARC) < −20 dB, Channel Capacity Loss (CCL) < 0.4 bits/s/Hz, and Isolation < −15 dB for all resonating bands. The proposed TPMMIMOFA resonates at 2.85, 4.75, 6.3, and 7.81 GHz, and has gain of 1.79, 2.66, 4.19, and 3.97 dBi respectively and radiation efficiency(η) of 71%, 74%, 74%, and 78% respectively. Novelty lies in its simple design which provide isolation of more −15 dB at all operating bands without any additional use of isolation technique. The gain of the proposed TPMMIMOFA has been improved successfully with the help of multilayer structure. Proposed TPMMIMOFA is useful for various applications in S band and C band.

Physics with non-unital algebras? An invitation to the Okubo algebra

Abstract This paper discusses the potential application of the Okubonions, i.e. the Okubo algebra, within quantum chromodynamics (QCD). The Okubo algebra lacks a unit element and sits in the adjoint representation of its automorphism group SU(3), being fundamentally different from the more better-known octonions O. A physical interpretation is proposed in which the Okubonions represent gluons, the gauge bosons of QCD SU(3) color symmetry, while the octonions represent quarks. However, it is shown that the respective SU(3) symmetries for Okubonions and octonions are distinct and inequivalent subgroups of Spin(8) that share no common SU(2) subgroup. The unusual properties of Okubonions are suggested as a possible source for exotic QCD phenomena like asymptotic freedom and color confinement, though actual mechanisms remain to be investigated.

Design and modeling of a highly compact negative index floral shape metamaterial for flight navigation applications

The collision avoidance system (CAS) is a mandatory monitoring apparatus equipped in all aircraft to safeguard flight safety. The CAS scans the predefined regions in a systematic manner for a certain length of time to detect any approaching aircraft that could potentially pose a threat. Thus, CAS requires a focused multi-element radiator which can encompass the complete azimuth region. Recent years have seen a growing emphasis on enhancing the efficiency of CAS antennas because of several constraints, such as low gain (3.6 dB), larger dimensions, substantial side-lobe amplitude (− 7 dB), and challenges with beam adaptation. The current research strives to enhance the gain of a CAS antenna by incorporating the basic idea of metamaterials (MTMs). Therefore, a compact floral-shaped double negative (DNG) MTM design is proposed. The CAS antenna routes the signal throughout the complete azimuth region, so the designed MTM must be proficient to withstand its DNG characteristics for different incident angles. Hence, the proposed design is tested at various incident angles spanning between to along the azimuth region, at a deviation. The results indicate that the proposed structure retains its DNG behavior in the desired frequency range, regardless of the incident angles. The computed effective medium ratio of the structure is 13.47 at the CAS central frequency (1.06 GHz), highlighting its compactness and efficacy. Furthermore, to analyze the function of the structure on the antenna, the unit-element (UE) is expanded to a 5 × 4 array and deployed as an additional layer on the radiator at a predetermined distance. The addition of MTM to the radiator outperformed the conventional radiator by enhancing the antenna gain, by 2.6 dB, respectively. Additionally, to confirm the experimental findings, the UE and array designs are fabricated, and the fabrication results align closely with the simulation results.

A Single-Site Approach: Identifying the Micro-Level Influences on Nurse Retention.

Persistently high turnover rates reflect nurses' discontent. Although personal reasons, career advancement, and relocation are cited as the top reasons for departures, macro-level data overlook the organizational and unit-level factors that erode nurses' desire to stay. Survey methods were used for data collection. The analysis included statistical and qualitative methods. Salary, benefits, and work schedules were important in influencing nurses' decisions to stay, but their importance varied by career stage. Ergonomic aspects of nurses' daily work were key themes. Organizational and unit elements play enduring roles in job satisfaction. Critically examining nurses' work environment from meso- and micro-level ergonomic perspectives can enhance understanding of nurse retention and provide evidence to fine-tune retention strategies.

Machine learning based sucker rod pump fault diagnosis using motor power curve

Relevance. The complexity of monitoring and diagnosing the condition of underground structural elements of sucker rod pumping units and large economic losses when operating this equipment with defects not identified in a timely manner. Aim. Development of methods for detecting faults in a sucker rod pump that do not require the involvement of highly qualified personnel for diagnosis, using information that is easily available on the surface. Methods. Machine learning methods (Decision tree method, K-nearest neighbors method, Support vector machine, Naive Bayes classifier) using motor power curves. Results and conclusions. The paper demonstrates the possibility of detecting faults in a sucker rod pump based on machine learning methods. The study was carried out on the basis of a developed simulation model of a sucker rod pump, used to reproduce motor power curves, taking into account the impact of the features of various equipment operation scenarios. Being the fundamental energy source for the oil production, motor power is directly related to the real-time operating condition of the oil well, and the motor power curve is a reliable source with the ability to increase the efficiency of sucker rod pump diagnostic. To train the machine learning classifiers and evaluate their performance accuracy, a number of characteristics were used, obtained from motor power curves for six different pump operating states. Namely, operating coefficients were calculated, representing the ratio of the power integral at each of the four stages of the installation operating cycle to the power integral for the entire cycle. The results show that the considered approach allows for high accuracy in diagnosing the operating conditions of a sucker rod pump. The classifier based on the decision tree method showed the highest efficiency among the four studied classifiers in identifying all six types of faults (95.8%), and the support vector machine method showed as well very high efficiency (90.3%).

Synergetics Principles of the Regularity of the Development of Microcracks in Elements of the Friction Units

In the study of tribological processes the highly nonequilibrium states of crystal lattice arise inside the frictional contact. It is no longer described by Hooke’s law, and undergoes a local structural transformation, besides its movement toward the equilibrium occurs as a synergetic process. However, the application of purely synergetics within the framework of continuum mechanics, by itself leads to the conflicting conclusions. The synergetic principles and the fractal approach of physical mesomechanics allow to describe kinetics of the plastic deformation and fatigue of various materials under different loading conditions from a single point of view, including the cyclic loading of tribocoupling, controlling of points of the bifurcation. In this paper, the stress-strain state of brake disks of transportation vehicles is analyzed to prevent the occurrence of microcracks on their working surfaces and the model is developed for studying nonstationary friction modes and fracture of contacting elements. The concept of metal fatigue is developed within the framework of physical mesomechanics. The proposed model explains the change in the mechanism of crack propagation under conditions of low-cycle fatigue of metal-polymer friction pairs when air enters the crack, and leads to the oxidation of fracture surfaces with the formation of a film. Perhaps, in this case, the formation of surfaces with a subgrain structure occurs.

A combinatory approach of non-chain ring and henon map for image encryption application

Algebraic structures play a vital role in securing important data. These structures are utilized to construct the non-linear components of block ciphers. Since constructing non-linear components through algebraic structures is crucial for the confusion aspects of encryption schemes, relying solely on these structures can result in limited key spaces. To address this issue, a complex non-chain ring with combination of Henon map based algorithm is presented. This proposed work aims to enhance both security and key space by utilizing complex algebraic structures. In this study, we investigate the use of unit elements from non-chain rings, establishing a mapping from the group of units to Galois fields to enhance the algebraic robustness of the scheme. A substitution box is constructed from Galois field and is applied in image processing. For pixel mixing, the Henon map is employed, and the exclusive OR operation is performed using a key generated from image pixels and the substitution box. The algorithm’s performance is evaluated using standard parameters such as histograms, Structural Similarity Index Measure (SSIM), correlation analysis, and National Institute of Standards and Technology (NIST) tests. For S-box analysis, we apply the strict avalanche criterion (SAC), bit independence criterion (BIC), linear approximation probability (LAP), and differential approximation probability (DAP). This algebraic approach utilizes a robust and state-of-the-art image encryption system that is highly effective against potential attackers.

MESHING TRANSFERS IN AUTODESK INVENTOR

In order to improve the execution of drawings of gear elements in the Autodesk Inventor package, an approach to the presentation of geometric information in accordance with the requirements of current standards is proposed, based on the use of developed three-dimensional models of assembly units of gear elements in parametric shells. The basis for the development of the sketch geometry of parametric shells were the basic geometric parameters of the tooth crowns of the elements, since when making drawings of gear meshing elements, the images of the tooth crowns are made in violation of the requirements of current standards. In order to simplify the construction of drawings of gear elements in the Autodesk Inventor package, an algorithm was developed to provide geometric information through the developed three-dimensional models of the parametric shells of the gear crowns of their elements. That is, the geometric information is embedded in the parametric assembly units "gearing in shells". The algorithm is based on working with the parametric shells of the elements of the constituent units, where all the necessary geometric information is represented by a function of the main geometric parameters of real gear crowns. The method of parametric shells considers the issues of touching, implementation, methods of formation of such shells with detailed coverage of their properties and geometric parameters. The rigorous mathematical theory of parametric shells, which involves the joint processing of analytical and geometric information obtained on the basis of the geometry of the gear elements as forming elements, is characterized by generalization in approach and mathematical rigor. At the same time, the presence of toothed crowns of three-dimensional models of gear elements by meshing is ignored. The algorithm for simplified creation of gearing drawings involves making cuts based on sketches, adjusting contour lines and changing the properties of areas in accordance with the requirements of current standards. The library of parametric shells and the algorithm for creating working drawings of both elements and gearing are implemented in the educational process.

Highly Directive and High Gain Multiple Beam Reconfigurable Antenna for Base Stations

A directional pattern reconfigurable array with high gain is proposed in this paper in which each antenna element is an array of driven and parasitic arc dipoles. The elements can be selectively excited using RF switches and power dividers to produce high gain patterns in desired single or multiple directions. By providing optimum spacing to array elements via stacking, gain can be further improved by exciting multiple elements simultaneously. The array resonates at 5.8 GHz, which is an ISM frequency. The directivity and realized gain of the unit element are 12 dB and 10.2 dB respectively. We hereby present a configuration of stacked antennas suitably arranged on a mast, which can find application as a base station antenna for next-generation wireless communication systems to switch patterns having directivity 14.3 dB and realized gain 12.1 dB in multiple directions with a reasonable bandwidth of 500 MHz and efficiency of 70%.

Images-symbols of the elements in the phraseological linguistic picture of the world (based on the Ukrainian language)

The subject of the study is the features of the implementation of symbolic meanings of images-symbols of the elements in the phraseological picture of the world based on the material of the Ukrainian language. Research objectives: to identify phraseological units with components-names-of-elements from the phraseological composition of the Ukrainian language; to determine the place of phraseological units of the Ukrainian language of the studied group in the language picture of the world; to consider the characteristic manifestations of the implementation of symbolic meanings of components-names of the elements in Ukrainian phraseological units. The research methodology is based on a combination of theoretical and empirical approaches using the methods of analysis, generalization and synthesis. The scientific novelty lies in the fact that phraseological units with the components water, fire and earth are analyzed using the material of the Ukrainian language: the study of phraseological units associated with the designation of natural phenomena makes it possible to identify the features of the linguistic picture of the world and folk thinking and allows for a better understanding of the value attitudes and specifics of the worldview of the Ukrainian people. Over the centuries, the elements have personified various aspects of human life and nature, thereby creating a rich palette of images that are reflected in phraseology. The symbolic meaning of the image-symbol fire is most often realized in the meanings: destructive or dangerous force, intensification of feelings, anger, speed, test. The symbolic meanings of the image-symbol fire are represented in the phraseology of the Ukrainian language by the following semes: danger, speed, suffering, illness, anger, excitement, blushing, negative character traits, exaltation. Phraseologisms with the symbolic image of earth are often associated with the concepts of social status, respect, life.

Compression failure and energy absorption characterization of mortise and tenon modular cellular structures

Abstract Based on the modular structure, effects of different module filling methods and dovetail geometry parameters of module connection on the failure modes and energy absorption characteristics of the overall structure are investigated under uniaxial compressive loading. The results show that when the model filling modes are hexagonal and auxetic cell elements filling, the upper-left, lower-middle, and upper-right parts start deforming first, and the connecting parts are all subjected to shear failures. When the overall filling mode is half-filling, the growth rate of the force-displacement curve is more stable, and the efficiency of the compression force is larger. Energy absorption is better when the overall filling pattern of the model is hexagonal unit element filling. The efficiency of the compression force can be improved when the angle α of the connection part is 60° and the width of the connection part is 12mm. The energy absorption effect can also be improved when the angle α of the connecting part is 65°.

On hyperelliptic curves of odd degree and genus g with 6 torsion points of order 2g + 1

Let a hyperelliptic curve C of genus g defined over an algebraically closed field K of characteristic 0, given by the equation y2=f(x), where the polynomial f(x)∈K[x]is square-free and has odd degree 2g+1. The curve Ccontains a single “infinite” point O, which is the Weierstrass point. There is a classical embedding of C(K)into the group of K-points J(K)of the Jacobian variety Jof the curve C, identifying the point Owith the unit element of the group J(K). For 2≤g≤5, the article explicitly found representatives of birational equivalence classes such hyperelliptic curves Cwith a marked unique point at infinity Othat the set C(K)∩J(K)contains at least 6 torsion points of order 2g+1. It was previously known that for g=2there are exactly 5 such equivalence classes, and for g≥3an upper bound was known that depended only on the genus of g. We improve the previously known upper bound by almost 36 times.

Super Low Profile 5G mmWave Highly Isolated MIMO Antenna with 360∘ Pattern Diversity for Smart City IoT and Vehicular Communication

Super Low Profile 5G mmWave Highly Isolated MIMO Antenna with 360∘ Pattern Diversity for Smart City IoT and Vehicular Communication

Wideband and Low-Profile Array of Tightly Coupled Dipole Subarrays

This letter introduces a novel wideband, low profile, tightly coupled dipole subarray for wireless communication systems. The proposed subarray, composed of 3 × 3 unit elements, offers a planar structure with high aperture efficiency. The unit element is a bow-tie-shaped tightly coupled dipole antenna covered by a frequency-selective surface for wideband operation. Using power dividers with quarter-wave transformers, the proposed subarray achieved an impressive impedance-matching bandwidth of 28.6–41.6 GHz (37.8%). This wideband performance was maintained in a 4 × 4 array configuration as well. The antenna’s low-profile design (0.08λc) and high aperture efficiency (77.2%) set it apart from existing wideband patch array antennas, making it a promising candidate for future wireless communication applications.

Prototype Facial Response to Cute Stimuli: Expression and Recognition.

Cute, kindchenschema stimuli can evoke a suite of cognitive, physiological, and behavioral tendencies thought to promote caregiving. This research investigated facial expression elements associated with this response to cuteness and assessed the recognizability of an expression combining these elements. In Studies 1 and 2, participants at a community outreach event (Study 1, n = 19) and undergraduate students (Study 2, n = 103) showed spontaneous facial displays while watching videos/photos of baby humans and animals. These were Facial Action Coding System (FACS)-coded, revealing characteristic and statistically distinctive action unit elements of facial expression responses to cuteness. In six follow-up online studies (combined N = 962), including replications with Syrian refugees (n = 103) and Chinese samples (n = 222), a "cuteness prototype" expression combining all elements identified across Studies 1 and 2 (i.e., oblique brows, chin raise, lip tightening, and Duchenne smile) was commonly interpreted as a response to cuteness. These findings add to a growing literature about caregiving-focused motivational states and associated emotion/affect.

Energy based damage model for low-cycle fatigue of ductile materials

A uniaxial material model for fatigue damage accumulation, established on the connection of unit elements, is presented in this paper. Although these units are regarded as micro-elements in the proposed model, they are based on a hysteretic operator that enables calculating hysteretic energy loss as an analytical expression. Further, this unit element represents a mechanical model with elastoplastic damage behavior in function of strain. The second level of modeling is defined by the connection of these units (micro-elements) with different values of total energy dissipated at failure. By changing the distribution of dissipated energy limit, various fatigue damage evolution laws are developed. Calculation of total and hysteretic energy loss in one loading cycle is also affected by fatigue damage as the varying number of unit elements are been eliminated when their maximum dissipation energy is reached. Material parameters for the model were defined based on the experimental monotonic and cyclic stress-strain tests, still, detailed comparison was not performed as the main advantage and aim of the paper was the development of the method for assessment of damage evolution in fatigue analysis. On the other hand, the number of cycles to failure ( Nf) and total heat dissipation are compared in both qualitative and quantitative aspects with experimental results. Finally, based on the proposed model, mean strain and load sequence effect diagrams were constructed. It is shown that the proposed model can provide a reliable estimation of fatigue life in the low-cycle regime of loading. The maximum error for the calculated Nf was 3% for constant strain loading for experiments with strain amplitude less than 5%. In load sequence fatigue life estimation, the proposed model demonstrated good accuracy, with a maximum error of 34%. Further, obtained results were achieved with different types of damage evolution that could be defined for the same material and fatigue life.

Unraveling Lewis acid-base sites in defected MOFs for catalyzing dicyclopentadiene hydrogenation via a DFT study and descriptor exploration

Unraveling Lewis acid-base sites in defected MOFs for catalyzing dicyclopentadiene hydrogenation via a DFT study and descriptor exploration

Monitoring of thick-walled pressure elements to determine transient temperature and stress distributions using the measured fluid's pressure and wall's temperature

Monitoring of thick-walled pressure elements to determine transient temperature and stress distributions using the measured fluid's pressure and wall's temperature

ON THE ISSUE OF ENSURING THE OPERABILITY OF FREIGHT CAR AXLE BOXES

The article is devoted to analysing the reliability of freight car axle boxes. Wheelsets and axle boxes are especially important for ensuring the traffic safety of trains. The study examined cases of cars uncoupling from a train along the route due to technical faults resulting in delays in train movement. The analysis covered the period of 1995–2023. It found that failures of car axle boxes and automatic brakes predominated. After a significant decrease from 2000–2014, the number of roller axle box failures in recent years fluctuated at 30% of the total number of uncouplings. The analysis obtained a dependency for the change in car detachments due to roller bearing failures, calculated per 1,000 cars in the operating fleet. Despite fluctuations in the number of railcars, the safety level of operations in recent years remained virtually at the same level. The study highlighted that excessive heating accompanies damage in the elements of the axle box unit. It considered methods for detecting possible failures and their advantages and disadvantages. The authors identified the primary causes of axle box component failures. Cylindrical bearings and end mountings remain the most dangerous for failure probability. We demonstrated that the axle box design with cylindrical bearings has a fundamental flaw. Axial forces are perceived through the rolling friction of the ends of the rollers against the ring flanges, leading to the formation of ‘chevron’ scratches and dents on the roller ends, which are stress concentrators. The study established that the surface of the axle box housing is constantly in contact with the side frame of the freight car bogie and wears out. It results in pinching of the axle box body and contributes to the appearance of additional permanent forces acting on the axle box assembly. The end-bearing mounts are weakened and destroyed. Skewed rollers in the bearings cause fatigue failure of the rolling races. It leads to increased heating of the axle box assemblies and uncoupling of the car. A promising direction is the improvement of axle box bodies. Keywords: rolling stock, traffic safety, reliability, axle box assembly, roller bearing, axle box body, failure.

On the unit-Jacobson graph

In this paper, we introduce the unit-Jacobson graph, which is defined by the unit elements and the elements of the Jacobson radical of a commutative ring [Formula: see text] with nonzero identity. We give relationships between this new graph concept and some special rings such as [Formula: see text]-clean rings, [Formula: see text]-rings, local rings, and cartesian rings. Moreover, we investigate the concepts of the dominating set, diameter, and girth on the unit-Jacobson graph.