Special Combination Research Articles

Active disturbance rejection control for systems with uncertainties and noise using super twisting differentiator-based event-triggered ESO

This paper focuses on the noise suppression issue of high-gain extended state observer (ESO) for systems with uncertainty and unknown measurement noise in the active disturbance rejection control (ADRC) paradigm. A special combination of super twisting differentiator (STD) and event-triggered ESO is devised with a designed event-triggered mechanism. Specially, the proposed STD-ETESO incorporates a finite-time switching strategy, which improves the poor transient performance of the STD acting as a pre-filter to prepare relatively smooth signals for the ESO. The locally asymptotic boundedness of the estimation error can be guaranteed by the Input-state-stability (ISS) and existing research for the STD. The effectiveness of the proposed method is validated by a general example and a practical motion control system. Different integral criteria is introduced to evaluate the overall tracking accuracy and energy usage for comparison with existing different ESOs, which reveals the superiority of the proposed STD-ETESO in noise attenuation and disturbance rejection.

Flexural Behaviour of Reinforced Shotcrete beams Comprehending Waste Plastic Fiber

Abstract Wet-mix shotcrete is often used as a placement method in tunnelling and ground support. However, to date, only a limited number of studies have been identified the roles of waste plastic fiber (WPF) on wet-mix shotcrete mixtures. This experimental study show the flexural performance of reinforced shotcrete concrete members (beams) having waste plastic fiber, which may be considered as a new study. In order to achieve that, a manufacturing of wet-mix shotcrete machine has been developed to product special wet-mix shotcrete that will be used to cast reinforced shotcrete concrete members containing waste plastic fiber. Extensive attempts were done in this project to generate a special wet-mix shotcrete combinations using locally sourced waste materials like beverage bottles. The qualities of WPF shotcrete concrete (SC) were investigated in terms of fresh, hardened, mechanical, and bending behaviour, with extensive results analysis. Five SC formulations (0.25, 0.5, 0.75, 1.0, and 1.25) percent WPF content, as well as the control shotcrete (SC0.00), were used in the experiments. In addition, the flexural behaviour of SC beams casted from the same waste materials was investigated. The results revealed that all SC beams had almost similar flexural behaviour when compared to the creation of crack patterns, as well as the ductility index and stiffness. The maximum ductility index was 2.29 for SC0.25, while the minimum stiffness was 1.31 for SC 1.25 beam. The flexural resistance of SC beams show in beams deflection state, the primary crack with presence the waste plastic fibers was small, because of the resistance of plastic fibers to tensile stresses happening at a moment of growth the crack. It also shows that adding WPFs to SC up to (Vf=1%) results in a rise in the loads that cause initial cracks when compared to beams made with reference mix.

Development of an effective modeling method for the mechanical analysis of three-core submarine power cables under tension

The structural complexity of submarine power cables (SPCs) presents significant challenges in their local mechanical analysis. This paper introduces an advanced modeling method developed for analyzing the mechanical behavior of SPCs under tension, emphasizing both accuracy and efficiency. The method’s accuracy is validated through a comparison of simulation results with tension tests conducted on a three-core SPC sample. Efficiency is demonstrated by the superior calculation speed of our model relative to traditional full-scale models. This improved performance is achieved by adopting periodic boundary conditions derived from the homogenization method applied to slender beam-like structures, and by employing a specialized combination of elements to model the helical metal components within the SPCs. The resulting model provides robust capabilities for the mechanical analysis of SPCs under tension and demonstrates significant possibility in accommodating various other loadings.

Non-conventional Manufacturing using the EDAS Method

A process that uses mechanical energy is conventional machining. Alternative energy sources are used by unconventional machines. In non-conventional machining, the three main types of energy are thermal, chemical, and electrical. non-standard machining, also referred to as modern machining, is a machining technique that removes, deforms, and modifies the properties of materials such as plates by utilizing electricity, energy types include electromagnetic energy, bio fuels, acoustic energy, electrochemical energy, and thermal energy. Tools and work pieces are in direct touch during conventional machining procedures. The tool and indeed the work piece do not have to come into physical contact for non-traditional machining procedures to work. The distinctions between conventional and non-conventional machining processes are examined in this article. The lead phase is typically coated using a paste made from a combination of lead & lead oxide powder, additives, and the necessary amount of acid and water after the sulphated mixture has been reduced to a fine lead mass to achieve the requisite density. On the other hand, non-conventional machining uses the most recent and cutting-edge processing technologies. No materials or machine tools come into contact with each other throughout this operation. Electric beam, electric arc, plasma cutting, and infrared beam are a few examples of non-conventional tools in use. Complex forms can be machined using those atypical machining techniques, in part due to the utilisation of cutting-edge CNC technology. The usage of these procedures is frequently determined by the material's shear strength, for instance, when wear resistant alloys and special combinations are involved. In order to create complicated and exact shapes in materials like titanium, stainless steel, high - temperature short (HSTR) alloys, jute composites, ceramics, refractories, and other hard materials, nontraditional machining (NTM) procedures are now often used. The goal of the current investigation using mechanical composites is to ascertain its effect. Brazilian consumers' food purchase intentions are influenced by a variety of manufacturing techniques, brands, prices, and labels. high-grade vegetable oils. Solvents, which may be hazardous, are used in conventional manufacturing processes. The environment suffers as a result. Change Manufacturing procedures, which don't require solvent use might necessitate the use of cutting-edge technologies like plant genetic engineering. looking into the use of genetic modification utilised in food production has a greater potential for reducing environmental effect. The EDAS score primarily based on the space from the suggest agreement machine is the installed energy for a manufacturing plant. Experts' critiques and derived numbers do not trust each different concerning solar energy and geothermal electricity. Traditional, Genetic engineering, High, Sunflower and Green globe. Smart Restaurant, Restaurant Automation, Device-to-Device Communication, Near Field Communications based, Smart Cities and Cloud Computing. Non-Conventional Manufacturing. Green globe is got the first rank whereas is the Sunflower is having the Lowest rank. Non-Conventional Manufacturing. Green globe is got the first rank whereas is the Sunflower is having the Lowest rank.

Revolutionizing vascular health through the temporal convolutional transformer for drug screening and model evolution

Vascular illnesses include a spectrum of disorders affecting the blood vessels and continue to be major global health challenges. Vascular disorders are major worldwide health concerns that require ongoing development of drug screening models in order to find efficient treatment approaches. The ever-changing field of vascular health demands novel ways to medication screening due to the enduring difficulties presented by a variety of illnesses. This abstract explores a paradigm shift, highlighting the innovative role of the Temporal Convolutional Transformer (TCT) in redefining drug screening techniques and promoting model evolution. With its seamless integration of transformer mechanisms and temporal convolutional layers, the TCT is a revolutionary hybrid algorithm. Because of this special combination, the model can simultaneously identify spatial subtleties and capture temporal dynamics in complicated biological information. The temporal convolutional layers of the TCT are particularly good at revealing the sequential dependencies that are present in the development of vascular disorders. The model ensures a detailed knowledge of the developing nature of these diseases by analyzing temporal dynamics with skill. Simultaneously, the TCT’s transformer mechanisms enable a thorough examination of long-range interdependence and global interconnections. The TCT’s dual capability establishes it as a comprehensive solution by offering a nuanced perspective on spatial patterns that are essential for identifying the complexity of vascular health. The TCT is hybrid in the sense that it can learn features at several scales, supporting different temporal and spatial resolutions. This flexibility guarantees that the model may extract pertinent information at various scales, enhancing the characterization of the complex nature of vascular illnesses. The TCT is positioned as a holistic solution since its transformer mechanisms allow for a thorough investigation of long-range dependencies and global interconnections at the same time. This combined capacity offers a sophisticated viewpoint on spatial patterns that is essential for understanding the intricacies of vascular health. Moreover, the remarkable flexibility of the TCT to dynamic temporal scales is consistent with the dynamic character of biological processes, providing a strong and adaptable framework for drug screening. The TCT is used in many different fields of vascular disease research. The model performs well in image-based screening, collecting sequential dependencies over time and processing spatial information from medical imaging datasets. The TCT’s capacity to identify long-range dependencies is essential for molecular interaction research since it helps to clarify the complex pathways associated with vascular disorders. Its adaptability also extends to personalized treatment approaches, which allow for the efficient modeling of patient-specific data, including genetic information. The TCT is a revolutionary tool that will continue to evolve as drug screening models do. By integrating temporal convolutional and transformer mechanisms, its all-encompassing methodology provides a sophisticated and comprehensive approach to deciphering the intricacies of vascular disorders. Across all evaluated metrics, the proposed method achieves near-perfect accuracy of 98.45%, sensitivity of 93.45%, specificity of 98.43%, precision of 84.25, AUC of 99 % and F1 score values 96.01%, respectively. This abstract sheds light on how the TCT has significantly changed drug development approaches, opening the door for more focused and effective therapies in the field of vascular health.

Secondary crushing of droplets of water-oil emulsions

When fuel oil is supplied to an accurate chamber, its spraying process takes place due to injectors and sprinkler devices. This process is called primary droplet crushing. It is often not enough to burn fuel efficiently. Since the size of fuel droplets in the combustion chamber often reaches several millimeters, which increases underburning and leads to uneven burnout. In such cases, it is advisable to use secondary crushing of water-oil fuel droplets. Secondary crushing of droplets reduces the average size of droplets in the fuel spray torch by several times. At the first stage of secondary crushing of droplets, their collisions with each other in the jet are realized, after which the formed droplets are subjected to collisions with the walls of thermal equipment. At the next stage, pyrolysis of such droplets occurs at the periphery of the jet, which leads to the formation of solid particles and subsequent collisions of droplets of water-oil fuels with them. At the final stage, the formed secondary fragments are subjected to intense heating in the combustion chamber, which allows for micro-explosive grinding. The present study is aimed at studying the characteristics of secondary crushing of water-oil fuel droplets with the addition of specialized additives. The results of the conducted studies have shown that the use of an additive based on a special combination of positively and negatively charged ions reduces the size of fuel droplets by 25%. It has been found that when using such an additive, the ratio of the free surface areas of droplets increases several times with a combination of all secondary grinding modes.

Integer-locking condition for stable dual-comb interferometry in situations with fluctuating frequency-comb repetition rates

To make dual-comb interferometry usable in a wide range of applications, it is important to achieve reproducible measurement results even in non-ideal environments that affect the repetition-rate stability. Here, we consider dual-comb interferometry based on a pair of fully referenced optical frequency combs (OFCs) and investigate the impact of fluctuations in the OFC repetition frequencies on the peak position of the center burst in the interferogram. We identify a phase-locking scheme that minimizes the impact of these fluctuations through choosing a special combination of phase-locked frequencies, and the resulting type of operating condition is termed integer-locking condition. Under the integer-locking condition, the number of sampling points in each interferogram remains constant regardless of repetition-rate variations, and this enables more stable phase-resolved measurements in non-ideal environments. We demonstrate the application of this approach using absolute path-length measurements and discuss the accuracy limit imposed by the integer-locking condition. Our findings offer a strategy for robust dual-comb interferometry outside metrology laboratories.

Combustion characteristics of water-oil emulsion droplets with special additives

Relevance. Fuel oil application in power plants is characterized by increased values of underburning and anthropogenic emissions. One way to reduce anthropogenic emissions is the use of oil-water emulsions. Also, additional specialized additives are used to reduce anthropogenic emissions and improve fuel combustion characteristics. Aim. To determine the optimal fuel oil additive to reduce anthropogenic emissions and ignition delay times. Methods. The following additives: ION-M, Rosneft R503V3, Rosneft R502V1 (relative mass concentration 0.5%) were added to the water-oil fuel. The physicochemical properties of fuel oil M-100, as well as the elemental composition of CHNSO, were determined. The rheological characteristics of water-oil fuel compositions were established. Using high-speed photography, the droplet ignition delay times were determined. Using the gas analyzer, it was possible to prevent anthropogenic emissions. Results and conclusions. The results of the study showed that the additive based on a special combination of positively and negatively charged ions (ION M) reduces ignition delay times by 20–60%, when the gas temperature varies in the range from 700 to 900 °C. The addition of the additive based on fatty vegetable acids (P502B3) reduced the ignition delay times by 7–10%, when the temperature changed in the range from 700 to 900 °C relative to water-oil fuel. It was found that when using the P502B1 additive in water-oil fuel, it was possible to reduce the ignition delay times by 15–50%. It was determined that in the presence of combustion catalysts, water binds with heavy hydrocarbons and thus the release of volatile substances occurs faster, i. e. the supplied heat is not wasted on heating water into droplets, but evenly affects the entire volume of fuel. The results of the study of anthropogenic emissions showed that the use of additives when burning water-oil fuel reduces the concentrations of CO, CO2, NO, SO2 by 8, 6, 10 and 13%, respectively, compared to fuel oil.

Recursive integral terminal sliding mode control with combined extended state observer and adaptive Kalman filter for MEMS gyroscopes

AbstractThe recursive integral terminal sliding mode control with combined extended state observer (ESO) and adaptive Kalman filter (AKF) is proposed in this article for micromechanical system gyroscopes. To accurately estimate the unmeasured system states in the presence of measurement noises, external disturbances and system uncertainties, the special combination of ESO and AKF is proposed. The AKF is employed to deal with measurement noises and prepare necessary signals for the ESO, while the ESO constantly provides the updated estimate of the lumped disturbance for the AKF. Furthermore, a robust control scheme is designed by using the recursive integral terminal sliding mode variable. Simulation results verify that more accurate unmeasured state estimation and higher tracking accuracy are achieved under the proposed method.

(245) Epididymo-Orchitis as the First Presentation of Brucellosis in an Endemic Area

Abstract Introduction Brucellosis, which is also called Mediterranean or Malta fever, is an endemic enzootic disease and can involve various organ systems. It is commonly endemic in the Mediterranean countries and the Middle East. Epididymo-orchitis is a focal form of human brucellosis. Brucella species cause granulomatous orchitis usually presenting as an acute or chronic unilateral swelling of the testis. Patients rarely present to the clinicians with acute scrotum due to Brucellosis Epididymo-Orchitis (BEO) as an initial finding. Objective Our aim is to estimate the prevalence of the BEO among the cases diagnosed with Epididymoorchitis in our hospital over the last four years. Methods Retrospective study from 2015–2018 involving all cases diagnosed with Epididymoorchitis in our hospital. A total of 92 cases of Epididymoorchitis were diagnosed during this period. These cases presented to ER complaining of severe unilateral scrotal pain, swelling, fever and sweating. Local examination showed swollen enlarged testis and epididymis with marked tenderness. Brucella serologic test for both B abortus and B melitensis were requested routinely for all cases of epididymo-orchitis. Scrotal Doppler ultrasonographic examination was requested at initial diagnosis and after 2 weeks to exclude abscess formation. Results Out of 92 cases, 8 were diagnosed to have brucellosis (8.7%). The median age of patients was 32 years (range, 18–41 years). All patients had positive history of consuming unpasteurized dairy products, which is a risk factor for brucellosis. The diagnosis of brucellosis was made via positive serological testing results (Brucella abortus and melitensis). One case showed testicular abscess formation. All cases were given combination of tetracyclin and rifampicin for 6–12 weeks. Two cases required prolonged hospital stay due to testicular abscess formation in one and development of Brucellosis spondylitis in the other. Gentamycin was added for one week in such cases. Conclusions In endemic regions for brucellosis, we have to consider it in the workup of all cases of epididiymo-orchitis. The diagnosis is easy by positive serology tests. Positive cases need special antibiotic combination protocol for longer time and close monitoring for development of local complications or other systemic brucellosis manifestations Disclosure No.

The Effect of a Six-Week Course of Surya Namaskar Practice on Back Flexibility and Lumbar Flexion in Male College Students

Study purpose. The strenuous Surya Namaskar exercise programme has gained considerable popularity among contemporary yoga practitioners. Its special combination of yogic breathing techniques, asanas (postures) and dharana (focused mind concentration) helps to improve flexibility. The aim of this study was to investigate the effectiveness of an original six-week course of Surya Namaskar on back flexibility and lumbar flexion in male college students. Materials and methods. Thirty male college students aged between eighteen and twenty years were randomly assigned to treatment group (Surya Namaskar practice) (n=15) and control group (n=15). The treatment group performed Surya Namaskar practice for six weeks, while the control group did not participate in any treatment other than their regular activities for six weeks. Back flexibility and lumbar flexion of the subjects were assessed at the baseline and after six weeks. Results. Back flexibility and lumbar flexion increased in the treatment group after six weeks of Surya Namaskar practice. Conclusions. The current Surya Namaskar procedure contributes to the kinanthropometric well-being of male college students in terms of back flexibility and lumbar flexion. Surya Namaskar should be included in school and college curriculum because of its numerous physical and physiological benefits.

Supramolecular elastomers with high strength and low toxicity are suitable for safety protection

Elastomer with high strength and toughness, temperature resistance and low smoke toxicity have shown great application prospects in the field of safety protection. In order to meet the needs of high strength, high toughness and smoke toxicity safety, a high-strength structural elastomer is formed by introducing the integration of hard skeleton and soft elastomer, that is, two-dimensional black phosphorus with high flame retardant efficiency and bimetallic hydroxide with catalytic detoxification (BP-MA-LDH) as the hard skeleton, based on the special combination of internal hydrogen bonds. High strength supramolecular poly(Urethane) (SPU) elastomer was manufactured by molecular design. The high strength and toughness SPU elastomer also has a tensile strength of 53.77 Ma and a elongation at break of 715.26 %. The addition of 2.0 wt% BP-MA-LDH reduces the heat release rate of SPU by 58.84 % and the smoke production release by 61.54 %. In terms of flue gas toxicity inhibition, Fractional Effective Dose was used to evaluate the flue gas toxicity of elastomer composites, and the release of CO, HCN, oxynitride and other toxic gases were greatly reduced. The synthetic performance of SPU elastomer composites in strengthening and toughening, smoke suppression and toxicity reduction is much better than that reported by peers.

Fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters utilizing zero-line modes in a three-terminal device

Topological zero-line modes (ZLMs) with spin and valley degrees of freedom give rise to spin, valley and spin-valley transport, which support a platform for exploring quantum transport physics and potential applications in spintronic/valleytronic devices. In this work, we investigate the beam-splitting behaviors of the charge current due to the ZLMs in a three-terminal system. We show that with certain combinations of ZLMs, the incident charge current along the interface between different topological phases can be divided into different polarized currents with unit transmittance in two outgoing terminals. As a result, fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters are generated. The mechanism of these splitters is attributed to the cooperative effects of the distribution of the ZLMs and the intervalley and intravalley scatterings that are modulated by the wave-vector mismatch and group velocity mismatch. Interestingly, half-quantized transmittance of these scatterings is found in a fully spin-valley-polarized electron beam splitter. Furthermore, the results indicate that these splitters can be applicable to graphene, silicene, germanene and stanene due to their robustness against the spin–orbit coupling. Our findings offer a new way to understand the transport mechanism and investigate the promising applications of ZLMs.

Enhancement of Benzene Emissions in Special Combinations of Electronic Nicotine Delivery System Liquid Mixtures.

Electronic nicotine delivery systems (ENDS) are battery-powered devices introduced to the market as safer alternatives to combustible cigarettes. Upon heating the electronic liquid (e-liquid), aerosols are released, including several toxicants, such as volatile organic compounds (VOCs). Benzene has been given great attention as a major component of the VOCs group as it increases cancer risk upon inhalation. In this study, several basic e-liquids were tested for benzene emissions. The Aerosol Lab Vaping Instrument was used to generate aerosols from ENDS composed of different e-liquid combinations: vegetable glycerin (VG), propylene glycol (PG), nicotine (nic), and benzoic acid (BA). The tested mixtures included PG, PG + nic + BA, VG, VG + nic + BA, 30/70 PG/VG, and 30/70 PG/VG + nic + BA. A carboxen polydimethylsiloxane fiber for a solid-phase microextraction was placed in a gas cell to trap benzene emitted from a Sub-Ohm Minibox C device. Benzene was adsorbed on the fiber during the puffing process and for an extra 15 min until it reached equilibrium, and then it was determined using gas chromatography-mass spectrometry. Benzene was quantified in VG but not in PG or the 30/70 PG/VG mixtures. However, benzene concentration increased in all tested mixtures upon the addition of nicotine benzoate salt. Interestingly, benzene was emitted at the highest concentration when BA was added to PG. However, lower concentrations were found in the 30/70 PG/VG and VG mixtures with BA. Both VG and BA are sources of benzene. Enhanced emissions, however, are mostly noticeable when BA is mixed with PG and not VG.

Steady-state solutions of the Whittaker–Hill equation of fractional order

We investigate the steady-state solutions of the Whittaker–Hill equation, including a fractional derivative term. Using appropriate Fourier series, we characterize the behavior of the eigenvalue surfaces as a function of the differential equation parameters and describe the corresponding eigensolutions. We also examine the situation where the fractional derivative is zero to serve as a comparison for the fractional solutions. For some special combinations of the parameters, the fractional derivative term leads to the appearance of degenerate complex eigenvalues.

«Бриллиантовая рука» Леонида Гайдая: окаянные мысли за завесой юмора

The article deals with the genre features of L.I. Gaidai “The Diamond Arm”. It is noted that in this fi lm, in addition to a satirical denunciation of various shortcomings of Soviet reality, L.I. Gaidai gives a parody on numerous foreign and domestic fi lms, primarily fi lms about James Bond, foreign parodies of Bond and other spies, detective and crime comedies and individual comedy roles. The connection in the fi lm of numerous echoes with parodied prototypes required the director to turn to a special genre – the mockumentary fi lm, which began to actively develop in those years in Western cinema. Perhaps Gaidai’s “The Diamond Arm” turned out to be the fi rst domestic example of this genre. It is based on the technique of bricolage, which is expressed in a special combination of many borrowed plot situations and actors’ characters. The result is a believable story with easily recognizable intrigues and plot moves, made in the manner of realistic fi lming, without exact quoting of material borrowed from other fi lms, but with a recognizable reliance on it. Thanks to the layering of parodied plot details embedded in everyday situations that were widespread in the Soviet reality of those years, the director creates a story that is outwardly simple and understandable to the general public, unfolding in the frame. Thus, Gaidai managed to form a script, consisting entirely of parodied borrowings. The director offers not only to laugh at the so-called ‘individual shortcomings’, but also draws attention to conceptual criticism of the vulnerable aspects of the Soviet mass consciousness of the 1960s – over the main value priorities of the many-sided domestic bourgeoisie, focused on the life for ‘personal benefi t’. Accordingly, he criticizes precisely this ideal of false self-assertion, both by direct satirical denunciations of the negative aspects of Soviet reality, and by parodying models of acquisitiveness and personal comfort borrowed from the West, to which Soviet seekers of an easy life were committed.

Analysis of the stability of the Kuban river landslide slope involving the materials of landslide hazard monitoring

The article discusses the improvement of methods for calculating the landslide threat in the monitoring of landslide hazard areas on the Kuban River and the study of the possibility of their negative impact on the operated hydraulic structures. The growth of economic activity, intensive use of water resources in the Kuban River basin leads to a decrease in the bearing capacity of slopes and an increase in landslide phenomena. These processes are also observed in the basins of other anthropogenically developed rivers of the Russian Federation. Shore protection structures and their construction are justified on the basis of the limit state method in accordance with the requirements of SR 58.13330.2011. The stability of such structures should be determined by reference to the stability conditions of the entire slope taking into account all acting loads and impacts. To solve this problem it is very effective to use a complex of structures regulating the flow of the river, flow guides (dams made of selected rockfill), slope-strengthening ones, etc. Measures justifying economic activity on a landslide slope are very effective. The right slope of the Kuban River in the suburbs of Armavir, Krasnodar Krai is characterized by the fact that significant (more than 3 m) fluctuations in inter-level and flood flow of rare frequency are observed on this section of the river. Realizing anti-landslide and bank strengthening measures it is necessary to provide for both a reduction in general and local erosion of the left bank and the drainage of groundwater and surface from the anthropogenically developed area adjacent to the right slope of the river Kuban. The purpose of this research is to substantiate the stability of the right slope of the Kuban River in the vicinity of the city of Armavir, Krasnodar Krai, where initial collapses are already taking place in connection with the construction of residential buildings in the immediate vicinity of the bank and the development of general and local erosion of the right bank of the river. The calculation is carried out according to several methods for the basic and special load combinations. These calculations are necessary to substantiate landslide and bank protection measures on the right bank of the Kuban River.

Auxetic mechanical metamaterials with symmetry-broken Re-entrant units

Three innovative auxetic metamaterials with symmetry-broken unit cells and possible applicability in the construction and automotive industries are presented by breaking the mirror symmetries of the conventional re-entrant unit cell. The single symmetry-broken re-entrant (SBR), double symmetry-broken re-entrant (DBR), and hybrid symmetry-broken re-entrant (HBR) structures are fabricated via 3D printing and examined by experimental compression tests and finite element analysis (FEA). The proposed metamaterials exhibit remarkable specific energy absorption (SEA) properties in comparison to the benchmark symmetric-unit honeycomb, with the SBR model showing 103.9 % higher SEA. The novel structures also show superior stability under large compressive deformation, exhibiting excellent auxeticity in comparison to the symmetric-unit model. Parametric investigations reveal that the level of asymmetricity of the unit cells plays a key role in the stability and superior mechanical properties of the proposed metamaterials under compression. One set of parametric studies discovers an HBR structure with a special combination of SBR and DBR units which outperforms the parent structures under compression. Finally, parametric investigation of transverse and inclined compression of the structures indicated superiority of the DBR metamaterial to other structures due to having a deformation mechanism with organized self-contact regions. The DBR metamaterial owns 314 % and 86 % higher SEA rather than the benchmark honeycomb under transverse and inclined compression, respectively.

Систематический обзор технологий производства металлической пены

Introduction. The paper presents a comprehensive overview of the manufacturing methods, materials, properties, and challenges associated with cellular metallic foams, primarily focusing on aluminum and titanium-based foams. Cellular metallic foams are gaining interest due to its unique combination of low density, high stiffness, and enhanced energy absorption capabilities. Cellular metallic foam is renowned for its special combinations of physical and mechanical characteristics, containing their increased stiffness, specific strength at high temperatures, light weight, and good energy absorption at relatively low plateau stress. It has extensive uses in the automotive, shipbuilding and space industries. It has high porosity, low relative density and high strength, which increases performance of the product. The aerospace and automotive industries require a material with a high strength-to-weight ratio. Methods. To meet this need, many metal foam production methods have been developed, such as melt route method, deposition method and powder metallurgy method. Melt route method is widely used to manufacture metallic foam as compared to other methods. Results and Discussion. In the production of aluminum foams, the melt route method is usually used. Titanium hydride (TiH2) has been a popular foaming agent, but its high decomposition rate and cost limitations have led to the development of alternative foaming agents, such as CaCO3 (calcium carbonate). Titanium foam is often manufactured using the space holder method. This method involves mixing titanium powder with a space holder material, forming a preform, and then sintering to remove the space holder and produce a porous structure as the space holder method allows for precise control over the properties of the foam, including pore size, porosity, and relative density. Results also indicate that porosity in cellular metallic foams can range from 50 % to 95 %, as reported in various journals. Pore structures can include mixed types, open cells, and closed cells, each offering different mechanical and thermal properties. It is also observed from various literature sources that relative density, which is the ratio of the foam's density to the bulk material's density, varies from 0.02 to 0.44 based on the production method used.

Alzheimer’s Disease: Novel Findings, Challenges and Implications for Healthcare Systems

AbstractBackgroundAlzheimer’s disease (AD) is a progressive, degenerative brain damage that impairs thinking and problem‐solving skills and causes memory loss as well as behavioural and emotional abnormalities. Amyloid plaques and tau tangles, aberrant protein clusters that cause cognitive deterioration, are the disease’s hallmark. The illness is a serious obstacle for the patient, their family, and caretakers, as well as for the healthcare system. This study aims to summarize the recent discoveries linking microorganisms and Alzheimer’s disease, the difficulties in confirming the theory, and suggestions on how scientists can improve alternative methods to study the underlying causes of AD.MethodAcademic publications were retrieved from the databases MEDLINE, Ebscohost, PubMed, Ovid, Embase, ScienceDirect, and Google Scholar using a unique search strategy. Emphasis was given to recent studies that provide insight into the current state, methods for diagnosis, and treatment options. Keywords in special combinations were used to retrieve information from various databases.ResultEvidence suggests that viruses can cause an increase in β‐amyloid peptide synthesis and tau phosphorylation, leading to the formation of senile plaques and neurofibrillary tangles. The absence of experimental evidence connecting microbes to the cognitive deficits and neuropathological alterations of AD, as well as the ambiguous composition and origin of the amyloids observed in senile plaques, are a few of the difficulties that researchers must overcome.ConclusionFurther research is pivotal in shaping the future of Alzheimer’s disease to fully comprehend the disease mechanism and treatment challenges. The development of tools to understand the complexity of the disease pathogenesis and its multifaceted aetiology is crucial. Additionally, in people who are predisposed to certain infections, early diagnosis of such infections may help delay the start of AD.