This study examined the impact of environmental factors on the quality of pipe-borne water used in Eliozu community, Rivers State, South-South Nigeria. Water samples were collected from two supply points and analyzed under standard laboratory conditions for key physicochemical parameters including pH, temperature, dissolved oxygen (DO), electrical conductivity, total dissolved solids (TDS), phosphate, chloride, alkalinity, turbidity, nitrate, and sulphate. Findings revealed that the pH values (5.80 and 5.50) were below the permissible WHO range (6.5–8.5), indicating acidic water with potential risks of pipeline corrosion and adverse health effects. DO levels (1.50 mg/l and 2.50 mg/l) were also far below recommended limits (4–6 mg/l), suggesting organic pollution and possible microbial contamination. Electrical conductivity (1.27 μS/cm and 9.00 μS/cm) and TDS (0.86 mg/l and 11.25 mg/l) were considerably lower than WHO limits, classifying the water as soft and deficient in essential minerals. Phosphate concentration (0.24 mg/l) exceeded the WHO threshold of 0.1 mg/l, pointing to anthropogenic pollution sources. Conversely, chloride, alkalinity, turbidity, nitrate, and sulphate levels were within safe limits, reflecting partial compliance with water quality standards. In conclusion, while the water samples met some physical standards, chemical imbalances pose potential health hazards. It is recommended that regular monitoring, treatment, and community sensitization be prioritized to ensure safe drinking water supply in Eliozu.

In the multi-objective optimization design of automotive seats, traditional single surrogate models often fail to achieve the required fitting accuracy when dealing with complex nonlinear responses, and the quality of optimal solutions obtained solely through global optimization algorithms remains suboptimal. To address these challenges, this paper proposes a novel hybrid surrogate model with enhanced predictive capability and integrates hybrid global optimization with gradient-based algorithms to further refine solution quality. Accordingly, an integrated optimization framework is developed, encompassing optimal Latin hypercube sampling, a hybrid surrogate model that combines the Pointer optimization algorithm with weighted prediction error reduction, and the archive-based micro genetic algorithm-Hooke-Jeeves combinatorial optimization algorithm, thereby establishing a comprehensive and systematic optimization strategy. The feasibility of this strategy is validated through an engineering case study on automotive seat optimization, demonstrating that the combination of the hybrid surrogate model and the combinatorial optimization algorithm offers notable advantages. Compared with classical multi-objective optimization strategies, the proposed method outperforms in terms of cost-effectiveness and lightweight performance, fully utilizes the design space for multi-objective optimization, and serves as a reliable reference case for future research. The research findings indicate that, compared with the original steel rear seat, the optimized version exhibits enhanced crashworthiness and a significant reduction in overall weight and material cost. Specifically, in terms of crash performance, the maximum displacement of the headrest frame is reduced by 3.81%, while that of the backrest frame remains well within the permissible range specified by relevant safety standards. Meanwhile, the seat’s weight and cost are reduced by 17.6% and 21.15%, respectively.

Type 2 diabetes mellitus (T2DM) accounts for about 90–95% of total diabetic cases which can be sustainably maintained by combined therapy. The goal of this study was to develop a bilayer tablet (BLT) that combines sustained release (SR) vildagliptin and immediate release (IR) canagliflozin to improve the treatment outcomes. Nine canagliflozin and six vildagliptin formulas formulas were tested. To determine the most appropriate formulations, the tablets’ physicochemical characteristics—hardness, friability, disintegration, and dissolution—were assessed. The in-vitro drug release study of BLT was conducted using 0.1 N HCl and pH 6.8 phosphate buffer (2 and 4 hours, respectively). For stability and compatibility tests, DSC, FTIR, SEM, and TGA were employed. F4 (74.60% release within 60 minutes) and A5 (89.76% release over six hours) were selected as IR and SR for BLTs. The physical parameters of the BLTs were within the permissible range, with an average weight of 381 mg, weight variability of 4.93%, thickness of 5.40 mm, hardness of 6.2 kg, friability of 0.32%, and a disintegration time of 18.2 minutes. The final bilayer tablet showed 81.34% release of canagliflozin within 1 hour and >80% release of vildagliptin within 6 hours, while no instability cases were recorded. The designed formulations revealed accepted in-vitro performance. Further development and in-vivo tests should be performed to ensure the desired outcomes. Dhaka Univ. J. Sci. 74(1): 127-137, 2026 (January)

Slag entrainment within the mold is a significant cause of surface defects in continuously cast slabs. As a key component for controlling molten steel flow, the structure of the submerged entry nozzle directly influences the flow field characteristics and slag entrainment behavior within the mold. This paper employs a 1:4-scale water-oil physical model combined with numerical simulation to investigate the effects of elliptical and circular submerged entry nozzles on slag entrainment behavior in a wide slab mold under different casting speeds and immersion depths. High-speed cameras were used to visualize meniscus fluctuations and oil droplet entrainment processes. An alternating control variable method was employed to quantitatively delineate a slag-free "safe zone" and a "slag entrainment zone" where oil droplets fall, determining the critical casting speed and critical immersion depth under different operating conditions. The results show that, given the nozzle immersion depth and slag viscosity, the maximum permissible casting speed range without slag entrainment can be obtained, providing a reference for industrial production parameter control. The root mean square (RMS) of surface fluctuations was introduced to characterize the activity of the meniscus flow. It was found that the RMS value decreases with increasing nozzle immersion depth and increases with increasing casting speed, showing a good correlation with the frequency of slag entrainment. Numerical simulation results show that compared with elliptical nozzles, circular nozzles form a more symmetrical flow field structure in the upper recirculation zone, with a left-right vortex center deviation of less than 5%, resulting in higher flow stability near the meniscus and thus reducing the risk of slag entrainment.

Introduction: During the construction of a tension wire across a live line, the pulled wire may fall and collide with the collision sealing net structure, posing a risk to the safety of the sealing device. It may also come into contact with, or in close proximity to, the live line, potentially causing a flashover. Therefore, it is very important to accurately obtain the changes in the strength and vertical displacement of the sealing net structure during the impact of falling wires for the design and construction of sealing net devices. Methods: According to the construction process of the overhead line, the accidental process of the broken line is analysed, and for the assumed defects of the existing simulation and the simulation difficulties, the sequence solution is introduced, and through the implicit-explicit sequence solution method, combined with the theory of nonlinear dynamic analysis, the simulation flow of the conductor-seal network collision is established. Results: Based on the relevant parameters presented in this paper, the equivalent load and the overhead line state equation were used to calculate the bending stress and cable tension under accidental conditions. The results showed that the bending stress in brace section 1 was -119.4 MPa, and the bearing cable tension was 32,329 N. These values differed from the simulation results by less than 5%, which is within the permissible error range, thereby demonstrating the feasibility and validity of the simulation calculations. Discussion: This study used numerical simulation to analyze the impact of a falling wire on the sealing network structure, highlighting displacement and stress changes. The implicit-explicit sequential solution method successfully simulated the entire process and addressed multi-step loading issues that traditional methods couldn't handle. The results provide key insights for sealing network design and advance transmission line construction safety research. However, the use of specific Dyneema ropes and epoxy resin sealing networks may limit the generalizability of the simulation results. Future studies should compare multiple materials and consider environmental factors affecting material performance. Conclusion: This study effectively addresses the multi-step simulation challenges related to structural prestressing and wire-network collision. The complete collision process between the wire and the sealing network has been accurately modeled and simulated.

This study investigates the valorisation of mixed municipal waste glass (MMWG; EWC 20 01 02) as a sustainable supplementary material in cement mortars. In contrast to most existing studies, which focus almost exclusively on homogeneous container glass, this work addresses a heterogeneous waste stream derived from municipal selective collection, containing flat glass, mirrors, ceramics, porcelain, and metallic residues. Such mixed household glass has not previously been systematically evaluated in cement mortars, thereby addressing a clear research gap. The MMWG was washed, dried, and ground in a Los Angeles drum with corundum abrasives to obtain a fine glass powder (FGP < 63 µm) with a median particle size of approximately 20 µm and a Blaine fineness of 360 m2/kg. Microstructural and chemical characterisation of the milled glass confirmed its highly amorphous nature and angular particle morphology resulting from grinding. In addition, coarse glass granules (0–4 mm) were used as partial replacements for natural sand in mortar mixtures. The incorporation of FGP led to a 4–12% reduction in flowability, attributable to the angular shape and increased specific surface area of the ground-glass particles. At 28 days, mortars containing 5–10% FGP exhibited mechanical properties comparable to the reference mix, while at 56 days their compressive strength increased by up to 8%, indicating delayed pozzolanic activity typical of finely milled, amorphous glass. Mortars containing coarse glass primarily reflected a filler and aggregate-replacement effect. Leaching tests conducted in accordance with PN-EN 12457-4 demonstrated that all mortars, both reference and MMWG-modified, complied with the non-hazardous waste limits defined in Council Decision 2003/33/EC. Minor exceedances of Ba and Cr relative to inert-waste thresholds were observed; however, these values remained within the permissible range for non-hazardous classification and were attributed to ceramic and metallic contaminants inherently present in the mixed glass fraction. Overall, this study demonstrates that mixed municipal waste glass—a widely available yet rarely valorised heterogeneous waste stream—can be effectively utilised as a finely ground supplementary material and as a partial aggregate replacement in cement mortars, provided that particle fineness is adequately controlled and durability-related effects are monitored. The findings extend the applicability of glass waste beyond container cullet and support the development of circular-economy solutions in construction materials.

Zinc (Zn) is an essential trace element that plays a key role as a cofactor for over 300 enzymes involved in metabolic processes, protein synthesis, and gene expression regulation. Zn supplementation is used in the prevention and treatment of infectious, dermatological, and reproductive system diseases. Legal regulations allow for a relatively wide range of mineral content in this product category (from −20% to +45% of the declared value). The study aimed to analyze the quality of food supplements containing Zn—compliance with declared Zn content was assessed. The study included 80 preparations. The preparations varied in terms of declared Zn content, pharmaceutical form, chemical form of Zn, composition, and primary mode of action. Zn content was determined by atomic absorption spectrometry after prior mineralization of the samples in concentrated nitric acid in a closed microwave system. It was estimated that 70% of food supplements contained Zn within the acceptable range. It should be emphasized that 23.75% of the preparations contained more Zn than the permissible range of Zn content, and 6.25% contained less—both of these groups of preparations may be associated with a health risk. From a regulatory perspective, these results highlight the need for continuous surveillance of the food supplement market to improve consumer safety.

Milk acts as an essential pathway for heavy metal contaminants mainly in regions influenced by coal mining activities. Research emphasizes on spatial, age based and interspecies differences and associated human health risks. Milk samples were collected from cows, goats and buffaloes reared in two coal mining regions from district Chakwal, Pakistan. Milk samples were analyzed for cadmium (Cd), zinc (Zn), copper (Cu), manganese (Mn), chromium (Cr) and iron (Fe) using atomic absorption spectrophotometry. Age related patterns revealed that Cd (cows: 0.11-0.25mg/L; goats: 0.13-0.18mg/L; buffaloes: 0.09-0.19mg/L), Cu (0.45-0.89; 0.36-0.54; 0.17-0.35mg/L), Cr (0.10-0.35; 0.30-0.36; 0.09-0.29mg/L) and Mn (0.35-0.68; 0.34-0.85; 0.60-0.72mg/L) concentrations increased with advancing age while Zn and Fe showed a declining trend. Spatial analysis displayed that milk samples from Choa contained higher concentrations of most metals compared to Minhala. Among the species, buffalo milk exhibited lower metal accumulation. Health hazard investigation based on estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and carcinogenic risk (CR) demonstrated higher hazard levels in children because of lessened body mass and greater milk consumption. In some cases, HI values for children exceeded the acceptable threshold (> 1) and CR levels for Cd and Cr surpassed permissible range (TCR = 0.0124). The results underscore potential of milk as a major exposure pathway for metals in coal mining regions and emphasize the requirement for constant inspecting and mitigation tactics to guard public health.

This study was carried out to determine the effect of partial supplementation Chlorella sp. on growth and survival in Labeo catla fry as protein source in 60 days of feeding trial. A completely randomized experimental design was developed with 5 treatments and four replicates. Chlorella powder was added to the basal diet at a 0% (control) (T0), 5% (T1), 10% (T2), 15% (T3) and 20% (T4) and fed to the Labeo catla fry. Sampling was carried out at every 15 days to monitor growth performance and to adjust rations. The water quality parameters viz. DO; alkalinity, pH and temperature were found in the permissible range during entire experimental period. At the end of feeding trial weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio and proximate analysis of fish carcass were evaluated. Growth performance, FCR, SGR, and PER of fish affected by Chlorella sp. supplementation. Survival rate was not affected by different amount of chlorella. Treatment T4, including 20% Chlorella in diet showed highest mean body weight, SGR, PER than those fed with other diets. FCR was lowest in treatment of Chlorella diet than control diets. In the proximate analyses of the fish showed highest protein in T4 (16.92%), fat in T4 (3.44%), ash in T4 (4.39%) and moisture in T0 (80.98%). results of the present study clearly showed that Chlorella sp. could be considered as a protein source for incorporation in Labeo catla fry diets to gain more weight.

The accuracy and reliability of measurement results for controlled parameters are essential for ensuring the quality of engine repairs. However, current standards, such as GOST 10448-2014 (“Piston Internal Combustion Engines”) and GOST 14846-2020 (“Automobile Engines: Bench Test Methods”), do not specify requirements for the permissible error in the indirect measurement of engine power. This study aims to develop metrological recommendations to achieve specified levels of reliability for measurement data obtained during the acceptance testing of repaired engines. Using probability theory, the authors derived a formula to calculate power measurement errors and established permissible error limits for various ZMZ engine models. A comparative analysis was performed to compare these calculated limits with the actual errors observed during running-in tests on GOSNITI test benches (models KI-5274, KI-5540М, KI-5541М, KI-542М, and KI-2118А). The results indicate that the actual measurement errors remain within the calculated permissible range (derived from the GOST-based methodology). To enhance the reliability of power control, the authors developed recommendations for calculating acceptance limits with an offset relative to the nominal power value. Permissible error margins and acceptance limits were determined for various ZMZ engine models based on the required reliability levels. The application of this methodology will improve measurement quality and the overall reliability of control results during the acceptance testing of repaired engines.

The experience of conducting modern military conflicts has shown that fire damage is carried out not only to the entire depth of the defense construction of active groups of troops, but also to critical national infrastructure objects (CNIO). The results of the analysis of recent studies and publications show that in the subject area much attention is paid to the problematic issues of using protective elements of defensive structures. Moreover, the issues of using protective structures such as partially penetrating screens (PPS), which are used during the engineering protection of CIO elements, have not been fully investigated. The article substantiates the rational parameters of PPS during the engineering protection of critical elements of CNIO. The organizational and technical aspects of effective engineering protection system are considered. In accordance with the concept of the “Fortress Country” developed by the authors, options for using PPS are proposed, the parameters of which are selected in accordance with the results of calculations taking into account the numerical values of the pressure on the front of the explosive shock wave and fragments of the warhead of modern enemy air attack means. In addition, optimal design solutions are proposed, which are profiles from a sufficiently narrow permissible range for the selected initial parameters. Examples of successful operation of PPS on level 2 engineering protection structures are given, and the effectiveness of their counteraction to missile fragmentation is shown. In cases where remote PPS were installed, airborne explosive wave did not cause any significant damage to critical elements (electrical transformers) inside the structures of protection level 2. Rapid replacement of damaged PPS with new ones allows maintaining continuity of protection and survivability of protective structures, and the high maintainability of PPS metal structures helps reduce operating costs for protection.

In this study, 240 juvenile Clarias gariepinus fish fed three locally manufactured fish feeds (F2, F3, and F4) as well as a foreign feed (F1) were examined for growth performance and nutrient consumption. Three treatments and a control were administered in triplicate during the twelve (12) week investigation, which used a completely randomized design. Water samples and morphometric measurements were collected biweekly. The objectives of this study were to determine the growth performance, nutrient consumption, survival rate, and cost-effectiveness of C. gariepinus fed three locally produced fish feeds and a foreign feed. The findings showed that the temperature, dissolved oxygen, and pH of the water were all within the permissible range. From the feeding trials, it was observed that all samples utilized the trial diets effectively. Nonetheless, the fish given F1 gained the most weight (185.73g), followed by F2 (170.24g), F4 (166.46 g), and F3 (149.17 g). There was no discernible difference (p>0.05) in the fish's weight growth after consuming various feeds. The SGR showed no significant difference, where F3-fed fish had the lowest specific growth rate (3.27), whereas F4, F2 and F1-fed fish had 3.39g, 3.44g and 3.53g, respectively. Fish fed F3 had the highest survival rate (93.33%), while fish fed F4 had the lowest (88.33%). However, fish fed F1 had the highest feed conversion ratio (1.42), while fish fed F2 had the lowest (1.29). Significant difference was not observed in FCR and survival rate (p>0.05) across fish that were fed various feeds. Despite fish fed F1 having the highest SGR (3.53), it had the lowest net profit (₦−87.45), whereas F4 yielded the highest net profit (₦80.41, p<0.05) followed by F2 (₦11.6) and F3 (₦4.75). This study revealed that although the foreign feed (F1) had the best growth performance and nutrient utilization, locally manufactured feeds can be more profitable for fish farmers because they are lower in cost than foreign feeds.

This study evaluated the physicochemical quality of two drinking water samples collected from the Addis Ketema borewell and Arba Rakkatte, and designated as AK and AR, respectively, to evaluate their compliance with the World Health Organization (WHO) and Ethiopian Compulsory Standards (ECS) for potable water. Thirteen parameters were analyzed, including pH, total dissolved and suspended solids (TDS and TSS), chemical oxygen demand (COD), total hardness (TH), calcium (Ca), magnesium (Mg), alkalinity, and selected trace metals (Mn, Ni, Fe, and Zn). The results showed that the pH values (6.92–7.01) were within the permissible range, while TDS (470–560mg/L) and TSS (0mg/L) indicated good mineral balance. The COD values were zero, suggesting the absence of organic pollution. However, total hardness values (382.08–418.56mg/L) slightly exceeded the Ethiopian limit (300mg/L), primarily due to high calcium and magnesium concentrations. All trace metal concentrations (Mn, Ni, Fe, Zn) were well below permissible limits, indicating negligible contamination from metallic sources. Overall, both samples met the essential WHO and ECS requirements, except for hardness, which categorizes the water as <i>very hard</i> but not harmful to health. The findings confirm that the water is safe for drinking and household use; nevertheless, mild softening treatment is recommended to improve domestic suitability.

Water is one of the most important elements for sustainability and maintenance of life. Its quality affects living beings both directly and indirectly. Surwal dam reservoir is an earthen type of reservoir situated nearby city of Sawai Madhopur. Main purpose of reservoir is for irrigation. Study on water parameters would help in assessment of water quality which is being used for irrigation in agricultural lands. Assessment of water quality will be helpful in sustainable agriculture practices, ensuring healthy crops and surrounding environment. Study was conducted during winter season when water of the dam was used for irrigational purposes for nearby agricultural lands. Statistical interpretation like Sodium Adsorption Ratio, Kelly’s ratio, Percentage sodium, and Chloro-alkaline indices, were used to analyze the water quality. Water quality parameters during the study period (October, 2024 – January, 2025) were within the permissible range, suggesting its suitability for irrigation purposes.

An analysis of the factors determining the efficiency of automobile transport systems using mathematical methods has been conducted. The most influential indicators reflecting the quantitative characteristics of this complex system have been identified, allowing for an assessment of the degree of correspondence between the actual results of transport operations and the desired outcomes. It has been shown that the efficiency of such operations can be evaluated using various mathematical methods. By applying these methods, it is possible to determine the probability of the transport system’s reliable operation over a specific period if the goal of transport operations is to enhance their quality and reliability. The factors considered in the study of the efficiency of automobile transport systems have been identified. It has been demonstrated that a significant portion of these factors is beyond the control of the decision-maker. These factors have been categorized, and a detailed classification has been provided. It has been revealed that in the study of automobile transport systems involving factors with stochastic variability, probability-statistical mathematical methods are widely used. These methods allow for determining the distributions of random variable factors. At the same time, assessing the efficiency of transport system operations while considering factors of a non-stochastic nature, which are uncertain, is significantly complicated by the lack of a general mathematical theory that forms a methodological basis for studying phenomena with uncertain factors. However, the application of applied mathematics methods, such as game theory, decision- making theory, and fuzzy set theory, enables the development of solutions to problems under conditions of uncertainty of a non-stochastic nature. The concept of membership functions has been examined from the perspective of elements of crisp and fuzzy set theories. Various forms of such functions in both analytical and graphical representations have been presented. It has been noted that these functions define a certain subset or subregion of the overall permissible range of factor variations. It has been determined that the subregion defined by the membership function, in a certain sense, reflects the degree of uncertainty of the studied factors. It has been shown that the smaller the subregion determined by the membership function, the lower the degree of uncertainty of the factors. It has been established that a fuzzy set is fully described by its membership function and is used to represent a large and imprecisely defined set of factors. It has also been found that a fuzzy set is empty if its membership function equals zero for all elements of the transport system. The transformation of uncertain random factors affecting the efficiency of automobile transport systems has been examined using the method of randomization. This method can be analyzed through a combination of probability theory and mathematical statistics methods.

Objectives: The increasing prevalence of overweight and obesity among Indian adults is now a recognized health concern. The concern is equally alarming in Armed Forces personnel. Assessment of the prevalence of overweight and obesity in a representative sample of serving Armed Forces personnel and its correlation with age, rank, and abdominal girth was the desired objective. Material and Methods: A cross-sectional point prevalence study was conducted in July 2023 across nine data collection centers. Using a convenient sampling technique, anthropometric data, including height, weight, and abdominal girth at the umbilicus, were collected from 1388 serving personnel. BMI was calculated, and data were stratified by age and rank. Results: Of the 1388 participants, 70.24% were within the normal permissible weight range. The prevalence of overweight and obesity combined was 29.8%, with officers showing the highest rates. Statistically significant correlations were found between body mass index (BMI) and age ( P = 0.024998), as well as abdominal girth and both age ( P < 0.00001) and BMI ( P < 0.00001). Rank-based BMI differences were not statistically significant. Conclusion: Substantial portions of serving personnel are either overweight or obese, with a clear association to age and abdominal girth. These findings underscore the need for targeted health and fitness interventions to preserve the health of the Armed Forces personnel.

Traditional fish smoking methods often raise significant concerns regarding product safety, quality inconsistency, and environmental pollution. This study aimed to evaluate a modified Efhilink smoking cabinet designed to address these issues by utilizing agricultural waste, specifically corn cobs and coconut shells, as bio-smoke sources for producing high-quality, safe smoked fish compliant with the Indonesian National Standard (SNI 2725:2013). Three fish species (mackerel tuna, Euthynnus affinis; flying fish, Cypselurus spp.; and ray, Dasyatis spp.) were processed using the modified cabinet and a traditional cabinet (control) and subsequently analyzed for sensory properties, proximate composition, histamine, TVB-N, pH, total phenolic content, and various contaminants (microbiological, heavy metals, chemical residues, and polycyclic aromatic hydrocarbons (PAH4)). The results demonstrated that all smoked fish samples from the modified cabinet met all critical parameters of the national standard. Coconut shell smoke generally yielded superior products, characterized by higher acceptability in aroma and taste, a greater infusion of phenolic compounds (up to 0.334 mg/kg), and significantly lower levels of PAH4 contaminants compared to the traditional control. All samples from the modified cabinet exhibited histamine levels well below the 100 mg/kg safety limit (12.36–19.37 mg/kg), total plate counts within the permissible range (10 to 3.6x10? CFU/g), and a complete absence of detectable pathogens (E. coli, Salmonella spp., S. aureus, V. cholerae) or hazardous chemical residues (chloramphenicol, malachite green, nitrofuran); heavy metal contaminants were also found at levels far below the maximum allowable limits. The modified cabinet significantly outperformed the traditional method in reducing PAH4 contamination. The technology not only enhances food safety but also promotes sustainable practices by converting agricultural waste into value-added products. In conclusion, the modified Efhilink cabinet, using either corn cob or coconut shell bio-smoke, effectively produces safe, high-quality smoked fish that complies with stringent food safety standards, with coconut shells demonstrating superior performance as a smoke source by enhancing sensory attributes and bioactive compound content while minimizing hazardous contaminants.

As the core component of new energy vehicles, the performance of the steering axle will directly affect the overall maneuverability, stability, and safety of vehicle driving. The structural performance indexes of the steering axle of the pure electric vehicle are analyzed by the finite element method, and a reasonable improvement plan is given according to its shortcomings. Firstly, the 3D model of the steering axle is established by SolidWorks (SOLIDWORKS 2023), and the details are simplified appropriately and then imported into the ANSYS (ANSYS2020R2 software) platform for static force analysis and modal analysis. Then, the stress distribution, deformation, and the first six orders of intrinsic frequency values of the steering axle are calculated and analyzed by using four working conditions, such as regular driving, emergency braking, lateral slip, and uneven road excitation, and it is concluded that the maximum stress of the original structure under each working condition is less than the requirement of the ultimate stress value. However, from the results, the maximum stress value is concentrated in the emergency braking condition and appears in the intermediate beam corner and the steering knuckle journal, which is also the most dangerous condition. In the modal analysis, it is concluded that the intrinsic frequency of this symmetry structure is much larger than the excitation frequency, and it can produce better dynamic effects under the working conditions, and the dynamic performance is better. Based on this, combined with the results of the static analysis of the proposed new increase in the thickness of the intermediate beam to improve the structural strength of the improvement measures, for this symmetry structure, through the re-simulation of the effect of the most critical conditions (emergency braking), the maximum deformation of the steering axle has been greatly reduced. In addition, the overall stiffness of the symmetry structure has been greatly improved, while the maximum stress is still less than the value of the permissible stress range, and the modal characteristics of the structure has not been affected. The finite element analysis software can effectively evaluate the performance and improve the optimization of the steering axle, which has certain theoretical significance and engineering reference value.

Abstract Riprap layers are widely used to resist erosion and protect hydraulic structures, including bridge abutments, against scour and collapse effects. Though long ago used, failure mechanisms of these layers under bridge abutments are poorly studied. This research aims to investigate the stability of Riprap layers and identify failure mechanisms, including failure due to shear forces, winnowing failure, and edge failure under different hydraulic conditions. Physical and engineering characteristics of Riprap material, intercomponent interaction, interface friction forces between the layer and support filters, conditions of base support, hydraulic flow dynamics, and their impact on erosion and collapse of the layer are investigated. A case study of the Khasa Chai River was conducted to research the behavior of Riprap layers and identify the controlling factors of failure. Observations showed that stability of such layers depends primarily on rock grain size, layer thickness, gradation of grains, and anchoring mechanism, as well as the influence of turbulent flow at the base of the abutment. Research indicates the development of more accurate analytical and laboratory models to estimate the behavior of Riprap layers under various flow conditions for the purpose of improving protection designs and optimizing their effectiveness to withstand scour around bridge abutments. HEC-RAS was software that helped analyze how water moved in rivers. It created a cross-section of the river, showing details like how fast the water was flowing, its levels, and how much water flows. This information was important for understanding how water behaved and for choosing the right size of stones to protect bridges from erosion. To get the results, a specific equation used to calculate water speed, discharge, and hydraulic depth. According to the calculations using the Isbash equation, the particle size for which 50% is finer by weight is 0.592 m. This value was within the permissible range according to the specified range, confirming that the results met the approved engineering standards. Overall, using HEC-RAS help to ensure that the bridge pier was safe from water-related damage.

Aims. Recent eROSITA measurements of the radial profiles of the hot circumgalactic medium (CGM) in the Milky Way stellar mass (MW-mass) regime provide us with a new benchmark to constrain the hot gas around MW-mass central and satellite galaxies and their halo mass distributions. Modeling this rich data set with state-of-the-art hydrodynamical simulations is required to further our understanding of the shortcomings in the current paradigm of galaxy formation and evolution models. Methods. We developed forward models for the stacked X-ray radial surface brightness profile measured by eROSITA around MW-mass galaxies. Our model contains two emitting components: hot gas (around central galaxies and around satellite galaxies hosted by more massive halos) and X-ray point sources (X-ray binaries (XRBs) and active galactic nuclei (AGNs)). We modeled the hot gas profile using the TNG300-based products. We generated mock observations with our TNG300-based model (matching stellar mass and redshift with observations) with different underlying halo mass distributions. Therefore, we tested the CGM properties as a function of their host halo mass distribution. The point sources are described by a simple point spread function of eROSITA, and we fit their normalization in this work. In total, we fit the X-ray surface brightness profile with two free parameters: the normalization of satellites in more massive host halos and the normalization of the mean point source emission. Results. We show that for the same mean stellar mass, a factor ∼2× increase in the mean value of the underlying halo mass distribution results in ∼4× increase in the stacked X-ray luminosity from the hot CGM. Using empirical models to derive a permissible range of AGN and XRB luminosities in the MW-mass X-ray galaxy stack, we choose our forward model that best describes the hot CGM for the eROSITA observations. Our chosen model in the MW stellar mass bin is in good agreement with previous literature results. We find that at ≲40 kpc from the galaxy center, the hot CGM from central galaxies and the X-ray point sources emission (from XRBs and AGNs) each account for 40 − 50% of the total X-ray emission budget. Beyond ∼40 kpc, we find that the hot CGM around satellites (probing their more massive host halos with mean M 200m ∼ 10 14 M ⊙ ) dominates the stacked X-ray surface brightness profile. Conclusions. The gas physics driving the shape of the observed hot CGM (in stellar-mass-selected X-ray stacking experiments) is tightly correlated with the underlying halo-mass distribution. This work provides a novel technique to constrain the AGN X-ray luminosity jointly with the radial hot CGM gas distribution within the halo using measurements from X-ray galaxy stacking experiments. Implementing this technique on other state-of-the-art simulations will provide a new ground for testing different galaxy formation models with observations.