Replacement Of Components Research Articles

Can fusion energy be cost-competitive and commercially viable? An analysis of magnetically confined reactors

Driven from investments toward net zero transition global interest in fusion energy is growing. This policy perspective addresses challenges for its commercialization, given the potentially long timeframe to deployment and competing/complementary technologies. We focus on magnetically confined fusion power, specifically tokamaks, as the route to commercialization is clearer and there is some cost data available. For fusion to be competitive beyond 2040, costs will likely need to be at or below ∼$80–100/MWh at 2020 price. This will be hard to achieve for early fusion designs both small or large, for which modelling shows energy costs will be greater than $150/MWh even accounting for production learning. This is due to the low power availability from pulsed operation; frequent replacement of vessel components; and low efficiency power cycles. Technology improvements to improve both cycle efficiency and power availability, along with production standardization and long-life components, have the potential to reduce generation costs and enable magnetically confined fusion to be commercially viable. We therefore recommend focusing commercialization efforts on plants with higher thermal efficiency and potential for higher availability as these maximize the probability of fusion energy proving commercially viable. We also recommend that fusion energy be deployed within a proportionate regulatory regime that recognizes its relatively low radiological hazard. Finally, construction of fusion reactors should be planned in fleet/program terms, as commitment to constructing many units will be necessary for it to become commercially viable.

What Is the Risk of Dislocation and Revision in Proximal Femoral Replacement with Dual-mobility Articulation After Two-stage Revision for Periprosthetic Hip Infection?

Dislocation is a major complication of revision THA after two-stage exchange for periprosthetic joint infection (PJI). The likelihood of dislocation can be particularly high if megaprosthetic proximal femoral replacement (PFR) has been performed during a second-stage reimplantation. Dual-mobility acetabular components are an established way of reducing the instability risk in revision THA; however, the likelihood of dislocation for dual-mobility reconstructions in the setting of a two-stage PFR has not been studied systematically, although patients with these reconstructions might be at an increased risk. (1) What is the risk of dislocation and revision for dislocation in patients who underwent PFR with a dual-mobility acetabular component as part of two-stage exchange for hip PJI? (2) What is the risk of all-cause implant revision and what other procedures were performed (apart from revision for a dislocation) in these patients? (3) What potential patient-related and procedure-related factors are associated with dislocation? This was a retrospective study from a single academic center including procedures performed between 2010 and 2017. During the study period, 220 patients underwent two-stage revision for chronic hip PJI. Two-stage revision was the approach of choice for chronic infections, and we did not perform single-stage revisions for this indication during the study period. Thirty-three percent (73 of 220) of patients underwent second-stage reconstruction with a single-design, modular, megaprosthetic PFR because of femoral bone loss, using a cemented stem. A cemented dual-mobility cup was the approach of choice for acetabular reconstruction in the presence of a PFR; however, 4% (three of 73) were reconstructed with a bipolar hemiarthroplasty to salvage an infected saddle prosthesis, leaving 70 patients with a dual-mobility acetabular component and a PFR (84% [59 of 70]) or total femoral replacement (16% [11 of 70]). We used two similar designs of an unconstrained cemented dual-mobility cup during the study period. The median (interquartile range) patient age was 73 years (63 to 79 years), and 60% (42 of 70) of patients were women. The mean follow-up period was 50 ± 25 months with a minimum follow-up of 24 months for patients who did not undergo revision surgery or died (during the study period, 10% [seven of 70] died before 2 years). We recorded patient-related and surgery-related details from the electronic patient records and investigated all revision procedures performed until December 2021. Patients who underwent closed reduction for dislocation were included. Radiographic measurements of cup positioning were performed using supine AP radiographs obtained within the first 2 weeks after surgery using an established digital method. We calculated the risk for revision and dislocation using a competing-risk analysis with death as a competing event, providing 95% confidence intervals. Differences in dislocation and revision risks were assessed with Fine and Gray models providing subhazard ratios. All p values were two sided and the p value for significance was set at 0.05. The risk of dislocation (using a competing-risks survivorship estimator) was 17% (95% CI 9% to 32%) at 5 years, and the risk of revision for dislocation was 12% (95% CI 5% to 24%) at 5 years among patients treated with dual-mobility acetabular components as part of a two-stage revision for PJI of the hip. The risk of all-cause implant revision (using a competing-risk estimator, except for dislocation) was 20% (95% CI 12% to 33%) after 5 years. Twenty-three percent (16 of 70) of patients underwent revision surgery for reinfection and 3% (two of 70) of patients underwent stem exchange for a traumatic periprosthetic fracture. No patients underwent revision for aseptic loosening. We found no differences in patient-related and procedure-related factors or acetabular component positioning for patients with dislocation with the numbers available; however, patients with total femoral replacements had a higher likelihood of dislocation (subhazard ratio 3.9 [95% CI 1.1 to 13.3]; p = 0.03) and revision for a dislocation (subhazard ratio 4.4 [95% CI 1 to 18.5]; p = 0.04) than those who received PFR. Although dual-mobility bearings might be an intuitive potential choice to reduce the dislocation risk in revision THA, there is a considerable dislocation risk for PFR after two-stage surgery for PJI, particularly in patients with total femoral replacements. Although the use of an additional constraint might appear tempting, published results vary tremendously, and future studies should compare the performance of tripolar constrained implants to that of unconstrained dual-mobility cups in patients with PFR to reduce the risk of instability. Level III, therapeutic study.

Vertical variations in microbial diversity, composition, and interactions in freshwater lake sediments on the Tibetan plateau.

Microbial communities in freshwater lake sediments exhibit a distinct depth-dependent variability. Further exploration is required to understand their biodiversity pattern and microbial interactions in vertical sediments. In this study, sediment cores from two freshwater lakes, Mugecuo (MGC) and Cuopu (CP), on the Tibetan plateau were sampled and subsequently sliced into layers at a depth of every centimeter or half a centimeter. Amplicon sequencing was used to analyze the composition, diversity, and interaction of microbial communities. Results showed that sediment samples of both lakes could be clustered into two groups at a sediment depth of about 20 cm, with obvious shifts in microbial community compositions. In lake MGC, the richness component dominated β-diversity and increased with depth, indicating that the microbial communities in the deep layer of MGC was selected from the surface layer. Conversely, the replacement component dominated β-diversity in CP, implying a high turnover rate in the surface layer and inactive seed banks with a high variety in the deep layer. A co-occurrence network analysis showed that negative microbial interactions were prevalent in the surface layers with high nutrient concentrations, while positive microbial interactions were more common in the deep layers with low nutrient concentrations, suggesting that microbial interactions are influenced by nutrient conditions in the vertical sediments. Additionally, the results highlight the significant contributions of abundant and rare taxa to microbial interactions and vertical fluctuations of β-diversity, respectively. Overall, this work deepens our understanding of patterns of microbial interactions and vertical fluctuation in β-diversity in lake sediment columns, particularly in freshwater lake sediments from the Tibetan plateau.

Logistics and maintenance research activities for DONES facility

DONES is planned to operate on a continuous basis with only two beam stop periods per year for maintenance. The planned operational availability is 70 %, which calls for a carefully analyzed preventive maintenance. The purpose of the research is to propose a realistic and comprehensive logistics and maintenance plan. All the maintenance activities are included in a Maintenance Matrix based on the Plant Breakdown Structure of the project. This is the basis for the creation of a maintenance plan that will lead to a Work Schedule. Special mention within this matrix will be given to those Maintenance operations that must be included in order to comply with regulation. The need of replacement of components impose some requirements on the dimensions of architectural features of the main building such as doors, airlocks, corridors and shipping bays. To enable these replacements, the flow of materials has been developed and analyzed by an intralogistics simulation with AnyLogic. The results of this simulation lead to modifications on either the building or the components such that the replacements are feasible. The periodic replacement of an activated component has been analyzed using FMEA methodology resulting in proposals for the plant equipment designers as well as the remote handling equipment designers. Virtual reality simulations are used for a staged approach to the maintenance operation. The simulation of the HEBT scraper helped to define in detail each step or the maintenance operation. This tool has proven to be very useful to prompt changes in both the plant equipment design and the remote handling equipment. Also, the procedure of the operation itself can be refined and optimized. The conclusion of the research activities is the contribution to the definition of the building, plant equipment and achievement of the target availability.

Lexico-grammatic mechanisms of linguistic creativity in the speech of modern embroiderers

The subject of this article is the most frequent linguistic units in the speech of modern embroiderers, which arise as a result of deviations from the language norm and testify to the high linguo-creative potential of the craftswomen discourse. However, the author also draws attention to the lexical unit class that are characteristic of the embroiderers speech and have a terminological character. Productive models for creating new lexical units are subjected to a detailed analysis: suffixation, addition, contraction, truncation of a phrase, abbreviation. The analysis showed that the morphological suffixal way of word formation exceeds in the modern embroiderers speech, addition and abbreviation are represented to a lesser extent. In addition, it was found that one of the active mechanisms for the transformation of lexical units is semantic derivation, which leads to the expansion of the conceptual scope of traditional lexemes. In most cases, this process occurs as a result of metaphorical transfer. The author of the article also considers cases of proverbs transformation in the embroiderers speech, reflecting the special worldview of embroiderers, and also being an opportunity for free self-expression. Most of them are transformations of traditional Russian proverbs, and new variants in speech become more common than their prototypes – canonical proverbs. Changes in the construction-sources are determined by the craftswomen intentions and affect different levels — semantics and structure. At the same time, the replacement of the proverb component becomes the most frequent creative mechanism. The language material collected and analyzed by us allows us to conclude that the speech of modern embroiderers has a high linguistic and creative potential and a wide range of language game markers, indicating the emergence of a special subculture of craftswomen at the present time.

High Precision IGBT Health Evaluation Method: Extreme Learning Machine Optimized by Improved Krill Herd Algorithm

The insulated gate bipolar transformer (IGBT) is widely used in industry, aerospace, renewable energy and other fields, which requires high reliability. However, in the research field of IGBT health evaluation, there are still problems that the accuracy is not high enough and the reliability manager of IGBT cannot accurately grasp. In this study, an IGBT health status evaluation model based on improved krill herd optimized extreme learning machine (IKH-ELM) is proposed to accurately evaluate the health status of IGBT, provide guidance for timely replacement of components, thus reducing the failure probability and maintenance cost, and improving the system reliability. Firstly, the power cycle accelerated aging test, short pulse-high amplitude current test and thermal resistance measurement test are carried out to obtain the failure predictor parameters data of IGBT. Then, an IGBT health status classification method based on cloud model is proposed to make the health status assessment results more scientific. In addition, since the random selection of weights and thresholds of ELM affects the performance of the model, the krill herd algorithm is improved to optimize ELM for obtaining better prediction ability. Based on this, a prediction model based on IKH-ELM is established. Finally, the proposed model is proved to be more accurate and effective under the same experimental environment and the same index.

An evaluation of 3D printable elastics for post stroke dynamic hand bracing: a pilot study

ABSTRACT The rise of 3D printing allows unprecedented customization of rehabilitation devices, and with an ever-expanding library of 3D printable (3DP) materials, the spectrum of attenable rehabilitation devices is likewise expanding. The current pilot study explores feasibility of using 3DP elastic materials to create dynamic hand orthoses for stroke survivors. A dynamic orthosis featuring a replaceable finger component was fabricated using 3DP elastic materials. Duplicates of the finger component were printed using different materials ranging from low stiffness (low elastic modulus) to relatively high stiffness (high elastic modulus). Five stroke survivors with predominantly moderate hand impairment were recruited to evaluate usability and impact of orthoses on upper extremity function and biomechanics. No significant differences in usability were found between 3D-printed orthoses and a commercial orthosis. Increases in stiffness of the 3DP material reduced pincer force (p = .0041) and the BBT score (p = .043). In comparison, the commercial orthosis did not reduce pincer force but may reduce BBT score to a degree that is clinically significant (p = .0002). While preliminary, these findings suggest that a dynamic orthosis is a feasible clinical application of 3DP elastic materials, and future study is warranted.

Strategic aspects of business development under the conditions of circular economy

Nowadays, the transition of business to the principles of circular economy is not only relevant, but also inevitable. The world is changing very quickly, there are transformations and customer requests that respond to the threats and harmfulness of any irresponsible economic activity to the environment. The circular approach will make it possible to find effective ways to reduce costs and enter new markets, including foreign ones. The purpose of the study is to determine the current state and strategic aspects of business development in Ukraine under the conditions of the circular economy. Attention is focused on a significant increase in the future use of natural resources, which is connected with the post-war recovery of business, housing stock and lost things. Therefore, businesses should already take into account such costs due to the need to restore the national economy and ensure an acceptable standard of living of the population. The situation in Ukraine with the generation and management of waste from economic activity is analyzed. Although the state of affairs differs significantly by region. The main difficulties are related to the unsatisfactory condition of the MSW storage facilities and the high costs of new technologies. It was found that the largest amount of waste is generated in the processing industry, the mining industry takes the second place, and the third place is taken by agriculture, forestry, and mining. Therefore, it is assumed that, taking into account such a distribution, the implementation of the circular economy should start with these industries, especially the processing industry. Such a context actualizes the manufacturer's qualitative assessment of its potential for the transition to closed cycles of resource use in modern conditions. It has been established that increasing the effective use of raw materials and energy is achieved by: established control of raw materials and all stages of their use; replacement of raw material components with alternative and less toxic ones; a comprehensive approach to product quality management. The strategic aspects of business that should be planned by the manager under the conditions of the circular economy (choice of business location, production technology, choice of stakeholders, competitive policy and tax planning) are substantiated and analyzed. Keywords: circular economy, business, development, waste management, potential.

Effect of Walnut-Shell Additive on the Structure and Characteristics of Concrete.

The partial replacement of the mineral components of concrete with natural renewable analogues in full possession of the performance characteristics of the final material, allows not only the concrete-production process to be made more environmentally friendly and inexpensive, but also to solve an important task for the agricultural industry, which is that associated with waste disposal. The scientific novelty of the work is in the obtaining of new concrete compositions by the partial replacement of coarse aggregate with a natural analogue in the form of a walnut shell, which has the maximum ratio of the strength of the composite to its density, as well as in identifying new dependencies of strength and density and their ratio on the amount of replacement of mineral coarse-aggregate walnut shell. The main goal of this article was to analyze the effect of composition factors on characteristics of concrete with partial replacement of large aggregates with walnut shells and to search for the optimal compound that would make it possible to obtain concrete with a minimum decrease in strength characteristics with a maximum decrease in concrete density. Cubes and prism laboratory samples were made from concrete of normal density with the replacement of coarse aggregate by 5, 10, 15, 20, 25 and 30%, by volume. The main mechanical properties, such as density, strength (compressive, tensile, tensile strength in bending) of the concrete samples were studied. The investigation used standard methods and scanning electron microscopy. An increase into strength characteristics up to 3.5%, as well as the maximum ratio of strength to density of concrete, was observed at a walnut-shell dosage of 5%. Effective partial replacement of coarse aggregate with walnut shells leads to a reduction in the consumption of crushed stone by up to 10% and a decrease in the mass of concrete by up to 6%.

Revision total hip arthroplasty by a ceramic bearing surface after a third- and fourth-generation ceramic head or liner fracture.

Although rare, fractures of ceramic components are difficult to revise, mainly due to the presence of residual ceramic debris that can cause catastrophic wear of the replacement components. Modern ceramic-on-ceramic bearings are suggested to improve outcomes of revision total hip arthroplasty (THA) for ceramic fractures. However, there are few published reports of mid-term outcomes of revision THA using ceramic-on-ceramic bearings. We evaluated clinical and radiographic outcomes of 10 patients who received ceramic-on-ceramic bearings during revision THA for ceramic fractures. All patients but one received fourth-generation Biolox Delta bearings. Clinical evaluation was performed using the Harris hip score at latest follow-up, and all patients received a radiographic evaluation to analyze the fixation of the acetabular cup and of the femoral stem. Osteolytic lesions and the presence of ceramic debris were noted. After a mean follow-up of 8.0 years, there were no complications or implant failures, and all patients reported satisfaction with their implant. The average Harris hip score was 90.6. There was neither osteolysis nor loosening, but despite our extensive synovial debridement, ceramic debris was noted in the radiographs of five patients (50%). We report excellent mid-term outcomes, with no implant failures after eight years despite ceramic debris being found in a significant proportion of patients. We conclude that modern ceramic-on-ceramic bearings are an advantageous option for the revision of THA due to the fracture of initial ceramic components.

Experience from implementing digital twins for maintenance in industrial processes

The capability of estimating future maintenance needs in advance and in a timely manner is a prerequisite for reliable manufacturing with high availability in a production unit. Additionally, conducting planned maintenance efforts regularly and prematurely increases the service lifetimes and utilization rates of parts, which leads to more sustainable production. The benefits of predictive maintenance are obvious, but introducing it into a facility poses various challenges. In this study, digital twins of well-functioning machines are used for predictive maintenance. The discrepancies between each physical unit and its digital twin are used to detect the maintenance needs. A thorough evaluation of the method over a period of 18 months by comparing digital twin detection results with maintenance and control system logs shows promising results. The method is successful in detecting discrepancies, and the paper describes the techniques that are used. However, not all discrepancies are related to the maintenance needs, and the evaluation identifies and discusses the most common sources of error. These are often the results of human interaction, such as parameter changes, maintenance activities and component replacement.

Ethyl 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylate in the smiles rearrangement reaction: straightforward synthesis of amino acid derived quinolin-2(1H)-one enamines.

This paper describes the development of 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylate compound as a heterocyclic enols containing a Michael acceptor so that it participates in an Ugi-type multicomponent condensation through a Smiles rearrangement in replacement of acid components. The new four-component containing 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylate, aldehyde derivatives, amine derivatives and isocyanides process leads readily and efficiently to heterocyclic enamines. This report is an outstanding strategy for the preparation of new biologically structures containing peptidic or pseudo-peptidic with quinolin-2(1H)-one scaffolds.

Investigation of detonation spray deposited Cr3C2-NiCr cermet coatings for hard-facing applications

Austenitic stainless steels such as AISI-316 are widely employed in manufacturing engine tubular manifolds, regenerators, jet engine components, and chemical processing facilities. During operation, these components are subjected to intense corrosion and wear, which results in the replacement due to a decline in performance. Instead of total component replacement, detonation spray deposition for repair and restoration of such components can be performed to minimize the wear and corrosion of the components, which further increases the lifespan of the components. In the present study, detonation spray deposition of the Cr3C2-NiCr cermet powder on SS316 steel is evaluated. Cermet powder was chosen instead of metallic powders, because of its higher hardness, corrosion resistance and ability to resist high-temperature degradation. The generated coatings were defect-free and were having a thickness of ∼ 500 µm. Chemical composition, microstructures, Vickers microhardness, and electrochemical corrosion properties of Cr3C2-NiCr coating were evaluated. The hardness of the coating is 875 VHN and of the substrate is 210 VHN. The electrochemical corrosion of coating in 0.5 M NaC1 for 1hr has been carried out and the Photo Dynamic Polarization (PDP) curves/ Tafel plots showed.

Seismic performance of precast column-beam joint with artificial plastic hinge

To improve the seismic performance and repairability of precast structures, an artificial plastic hinge (APH) was proposed for precast beam-column joint. The proposed APH was made from a combination of steel and high-strength-concrete (HSC), and the AHP will dissipates energy through metal plastic deformation when the earthquake occurs. To carry out the research, three full-scale beam-column joints were designed and fabricated, including one cast-in-place joint and two precast joints with APH. By using hysteretic loads, the seismic performance of joint was examined. For more systematic research, the finite element models were established and verified, and the parameter analysis was carried out. The findings demonstrate that the proposed joint performs well in terms of ductility and energy dissipation. It is recommended to use 12 mm steel plate thickness in the actual design, and to ensure the number of connecting bolts to avoid connection damage under earthquake. Through design optimization, the damage to the APH will be revealed at the location of the replaceable steel components, so as to achieve rapid repair after the earthquake.

Analysis of surface integrity of intermetallic composite based on titanium-aluminum machined by laser cutting

Ti-Al intermetallic composite is a lightweight material with excellent mechanical properties, resistant to corrosion and oxidation, especially at high temperatures. It has the potential to be used in many industrial fields such as the replacement of nickel-based superalloy components in aircraft engines. The present paper treats the gas-assisted laser cutting of this composite material. It develops an experimental investigation on the effects of certain machining parameters namely laser output power and cutting speed on the surface integrity of cut edges. The main purpose of this experimental investigation is the optimization of the surface integrity of workpieces made of Ti-Al intermetallic composite, designed with the combination of thixoforming method and semi-solid powder metallurgy, when they are machined by laser cutting. The novelty of the present study is that the presented results demonstrated that the effect of these two parameters on the surface integrity is different to other materials, the best surface results are recorded at lower laser power and lower to medium cutting speeds.

Phase stability and tensorial thermal expansion properties of single to high‐entropy rare‐earth disilicates

AbstractTemperature limitations in nickel‐base superalloys have resulted in the emergence of SiC‐based ceramic matrix composites as a viable replacement for gas turbine components in aviation applications. Higher operating temperatures allow for reduced fuel consumption but present a materials design challenge related to environmental degradation. Rare‐earth disilicates (RE2Si2O7) have been identified as coatings that can function as environmental barriers and minimize hot component degradation. In this work, single‐ and multiple‐component rare‐earth disilicate powders were synthesized via a sol‐gel method with compositions selected to exist in the monoclinic C 2/m phase (β phase). Phase stability in multiple cation compositions was shown to follow a rule of mixtures and the C 2/m phase could be realized for compositions that contained up to 25% dysprosium, which typically only exists in a triclinic, P , phase. All compositions exhibited phase stability from room temperature to 1200°C as assessed by X‐ray diffraction. The thermal expansion tensors for each composition were determined from high‐temperature synchrotron X‐ray diffraction and accompanying Rietveld refinements. It was observed that ytterbium‐containing compositions had larger changes in the α31 shear component with increasing temperature that led to a rotation of the principal axes. Principal axes rotation of up to 47° were observed for ytterbium disilicate. The results suggest that microstructure design and crystallographic texture may be essential future avenues of investigation to ensure thermo‐mechanical robustness of rare‐earth disilicate environmental barrier coatings.

In Vivo Evaluation of the Position and Orientation of the Geometric Axis of the Tibiotalar Joint.

Fitting the surface morphology of the talar trochlea is one of the common methods to define the geometric axis of the tibiotalar joint (GATJ). However, the in vivo motion of such axis during gait has not been fully investigated. The ankle kinematic data of fifteen volunteers were collected by a dual fluoroscopic imaging system with a model-image registration method. The GATJ was defined by sphere-fitting the medial or lateral part of the trochlear surface of the talus. The position and orientation of this axis during gait were measured. To verify this axis, the distances of the feature points of the talus to the GATJ during gait were also measured. There was no statistically significant difference in the distances of feature points of the talus to the GATJ among the seven key poses of the gait cycle. And the position and orientation of the GATJ during gait also showed no statistically significant difference. The GATJ is the axis about which the talus rotated. And it is one fixed axis during gait. The current finding may help the design of the talar component for total ankle replacement based on the surface morphology of the talar trochlea.

Development of Mechanical Pipe-Connection Design for DEMO

Maintenance of the DEMO breeding blanket includes the removal and replacement of plasma-facing components. To access the breeding blanket, multiple coolant pipes need to be removed to allow access to the tokamak. As an option to reduce downtime and increase maintenance speed, the pipe-connection concept is developed to allow the removal of multiple pipes at the same time using a remotely operated mechanical connection. The remotely operated multi-pipe Mechanical Pipe Connection (MPC) needs to fulfil multiple requirements, such as high operating temperature and high external forces while at the same time maintaining an acceptable level of sealing between the high-pressure fluid and vacuum surroundings. In addition to the external conditions, the pipes of multiple sizes and fluids are connected in a manifold configuration. Although this will reduce the overall time required to operate the mechanical pipe connection when compared to multiple single-pipe connections, this will introduce additional forces and stresses due the interaction between pipe flow (e.g., simultaneous high- and low-temperature fluid pipes on the same manifold) through the manifold flange. The requirements and the boundary conditions of the multi-pipe MPC are taken into consideration during the design process of MPC. The design process is carried out to find the optimum form and size to allow the mechanical function of the pipe connection during the maintenance phase while withstanding the extreme operating conditions that the MPC will face the during operational phase. The resulting design will then be analyzed using numerical methods to assess the capability of the MPC designs.

Impact of Emission Control Systems for Heavy Equipment and Power Plants on Global Warming

The article outlines the study on emission control systems from various diesel engines. The study was carried out for the heavy equipment and power plants operations to meet the environmental regulations. The purpose of this paper is to examine various emission control systems, how it operate at low emission level and their malfunctions. As the world strive for global warming regulations, there is a need to consider various emission control systems operating at low emission level to minimize the problems of the environment hazards. Internal combustion engines are characterized for producing exhaust emissions, mainly used in industries, transportation, power production and machinery. CAT Caterpillar ET 2019C Diagnostic Electronic Tool was used on heavy equipment and Perkins EST 2018A v1.0 Diagnostic Tool used on the power generating plants to detect various faults on emission control systems. Most of the emission produce were from the defective emission control systems thus fuel injection pump, fuel injectors, induction and exhaust manifolds design, positive crankcase ventilating systems, turbocharger and catalytic convertors. The Study was conducted in Mali-Tombouctou Region within UN Mission area and to examine various types of heavy equipment and different capacity of power plants emission control systems, under Ghana Engineer Company serving and providing engineer support for the Mission. The study recommend that the replacement of component or system used for repair be genuine service part to maintain the quality for emission control systems. All emission control system parts must be scheduled for regular inspections. Any part that fails under operation need to be replaced or repaired to reduce emission. Owners and operators normally don’t comply with and report emission issues. The study adds to the existing knowledge of emission control in our environment to reduce associated environmental health issues and global warning.

Limitations in the existing models for predicting accurate interdependencies between wear and friction noise,

In recent years, the investigation of friction noise has gained increasing attention within the field of tribology. Wear processes pose a significant hurdle in the industrial sector as reduce the lifespan of machine components. The replacement of damaged components, including brake systems and high-speed running machines, incurs substantial expenses. Thus, there arises a need for a method capable of identifying alterations in surface contact conditions, enabling the monitoring of the process and anticipation of the noise and rate of wear. To directly measure wear, it would be necessary to remove one of the contact surfaces (i.e., mechanical contacts such as gears and bearings.) for visual inspection, resulting in significant downtime. Alternatively, indirect measurements of wear can be performed by assessing the emitted machine noise and establishing a correlation between the noise and the alteration in surface topography caused by wear progress. Friction noise refers to the acoustic emissions generated during the contact between rough surfaces in motion. These emissions contain valuable information about the dynamics and characteristics of the sliding surfaces. Therefore, the researchers have attempted to model the interdependencies in between friction, wear and noise to find out the mentioned information and mapped it with the surface health of the mechanical contacts. The objective of this research paper is to examine all the prominent current models to discuss their approaches about how the noise can be generated from friction and later generate surface wear. This paper mainly aims to highlight their key limitations and identify the current challenges in modeling the mentioned interdependencies with accuracy.