Low Maintenance Costs Research Articles

Towards Multiple Sources for Energy Harvesting in Wireless Sensor Networks in Practical Applications

For wireless sensor networks (WSNs) to continue operating, energy harvesting plays a critical role. This paper explores this topic. WSNs are essential to many applications, from industrial processes to home automation. The difficulty is in giving sensors enough power, particularly in isolated or difficult-to-reach places. A solution is found in energy harvesting, which uses vibration, heat, radio frequency, heat, and solar energy to power sensors. The wide range of uses for energy harvesting in climate change modeling, noise pollution mitigation, and environmental monitoring are examined in this paper. The emphasis now turns to real-world applications of various energy sources to improve WSN performance, with a particular emphasis on the switch from primary to rechargeable batteries. The study emphasizes how battery-free devices can lower maintenance costs and increase application possibilities. The field of energy harvesting, which includes thermal, radiofrequency, vibration, and solar energy, provides access to sustainable and priced WSNs. By elucidating the benefits of battery-free devices, this study underscores the potential to enhance WSN sustainability while simultaneously lowering operational costs. It underscores the transformative impact of energy harvesting, offering a pathway to sustainable and economically viable WSN deployments.

Detection of Cavitation in a Centrifugal Pump-as-Turbine Using Time-Domain-Based Analysis of Vibration Signals

Pumps-as-Turbines (PATs) are increasingly used in micro-hydropower applications due to their cost competitiveness that is brought about by lower acquisition, design, operation, and maintenance costs. Despite these, limited research exists that investigates PAT failures. Notably, there is a literature gap concerning cavitation in PATs. As such, this study proposes an improvement to the deviation from the normal distribution (DND) technique to facilitate application in PAT cavitation detection. Probability density functions of vibration signals collected during operation at design speed and various cavitation states are developed and the DND computed using two approaches, i.e., the use of baseline data and the original method, for comparison purposes. Normal probability plots are presented to depict suitability of the two approaches in quantifying the DND. Results show higher deviation when using baseline data, hence, improved detection capabilities with amplification of the slope of the trend line under cavitating conditions when using the proposed DND approach. The proposed method also allows for establishing clear alarm limits for the condition monitoring of PATs in practice. Moreover, the proposed method is validated by application at various PAT operating speeds and cavitation states. The proposed method is found to be responsive, reliable, and independent from operating speed.

Comprehensive Comparison of Traditional Engines and Emerging Alternatives

As the natural environment deteriorates, electric vehicles will gradually replace internal combustion engines that use traditional fossil fuels. This paper compares traditional engines to alternatives regarding efficiency, emissions, price, and market share. In brief, alternative engines have advantages over traditional internal combustion engines in terms of efficiency, emissions, and long-term overhead, as evidenced by rising market share. In 2022, the share of electric vehicles in global sales has reached 14%. Compared to traditional internal combustion engine vehicles, electric vehicles have a higher well-to-wheel efficiency, up to more than twice of internal combustion engine vehicles. From a price perspective, electric vehicles have a higher original cost. However, lower maintenance costs allow electric vehicles to achieve the same cost as equivalent combustion engines in 5-8 years. Electric vehicles typically have low well-to-wheel and fuel emissions and are more sustainable. In the future, more research and development are needed for electric vehicles to make them suitable for most cities worldwide. At the same time, research into the traditional internal combustion engine should be addressed, as cleaner, more efficient engines such as the HCCI engines are already available for civilian use.

Daily Living Activity Recognition with Frequency-Shift WiFi Backscatter Tags.

To provide diverse in-home services like elderly care, versatile activity recognition technology is essential. Radio-based methods, including WiFi CSI, RFID, and backscatter communication, are preferred due to their minimal privacy intrusion, reduced physical burden, and low maintenance costs. However, these methods face challenges, including environmental dependence, proximity limitations between the device and the user, and untested accuracy amidst various radio obstacles such as furniture, appliances, walls, and other radio waves. In this paper, we propose a frequency-shift backscatter tag-based in-home activity recognition method and test its feasibility in a near-real residential setting. Consisting of simple components such as antennas and switches, these tags facilitate ultra-low power consumption and demonstrate robustness against environmental noise because a context corresponding to a tag can be obtained by only observing frequency shifts. We implemented a sensing system consisting of SD-WiFi, a software-defined WiFi AP, and physical switches on backscatter tags tailored for detecting the movements of daily objects. Our experiments demonstrate that frequency shifts by tags can be detected within a 2 m range with 72% accuracy under the line of sight (LoS) conditions and achieve a 96.0% accuracy (F-score) in recognizing seven typical daily living activities with an appropriate receiver/transmitter layout. Furthermore, in an additional experiment, we confirmed that increasing the number of overlaying packets enables frequency shift-detection even without LoS at distances of 3-5 m.

Investigation of two phase liquid jet ejector with simultaneous air and water suction in fresh water distillation system

Liquid jet ejectors can be utilized to generate vacuum in thermal desalinations, power plant applications and chemical industries. Liquid jet ejectors have no moving parts and have the advantage of reliability and low maintenance cost and also entrainment of non-condensable gas and brine simultaneously relative to pumps. The aim of this work is to model a liquid jet ejector with mixed air and water suction, applicable in fresh water distillers. The design is numerically simulated by two-phase Eulerian model and Realizable k-ε turbulence model. The results of the numerical model of liquid jet-air ejector are compared with experimental data and good agreement is achieved with deviation of about 7.4 % and 11.2 % for flow ratio and maximum discharge pressure respectively. In order to study robustness of the design, the value of suction entrainment and motive load of ejector is studied for different values of brine and suction pressure (8–12.5 kPa) of a 12 m3/day fresh water distiller. The results show constant air entrainment in off-design condition. In addition, mixing behavior and hydrodynamics of the flow in such ejector is studied by the parameters of pressure, velocity, flow and turbulent intensity distribution and compared with the ejector with air-only suction.

Development of a Low-Cost Web-Based Information System for Managing a University Department Chemical Warehouse

Herein, we present the implementation of a low-cost web-based information system tailored to manage a university department chemical warehouse. The system provides a centralized platform for cataloging, tracking, and managing chemical inventory data, while also facilitating purchasing and various administrative tasks associated with laboratory operations. The system has been developed within the Campusnet platform and has the following functionalities: (i) an efficient way for cataloging the extensive array of products available in the warehouse; (ii) an intuitive web interface with a device-responsive layout to facilitate browsing and purchasing of products by students, researchers, and technical staff; (iii) an inventory transaction recording system to simplify the attribution of costs; (iv) a simple procedure to streamline the process of joint purchases; and (v) a low deployment cost and ease of maintenance. Key design considerations, including regulatory compliance and safety, are also presented.

Implementation of Internet of Things for Condition-Based Maintenance in Elevator Systems: An Analytical Case Study

The aim of this paper is to show how IOT technology can allow highly distributed elevator equipment servicing by using remote-monitoring technology to ease a move from tradi- tional corrective maintenance (CM) and time-based maintenance (TBM) to more prophetic, condition-based maintenance (CBM) in evidence to accomplish different advantages.The Literature review can indicate that CBM has merit over conventional CM and TBM from a theoretical outlook, but it turns on constant monitoring enhancement via advanced IOT technology. A detailed case history was implement to bring practical proof that IOT allows elevator adamant to attain CBM.Through, a theoretical context, the CBM of elevators put together exper- tise.The venture lies in data collection, data analysis and decision making in real-world context of business. The key outcome of this research recommends that in the case of elevators the IOT can be commercialized and would improve the welfare and accuracy of equipment. It might, so, be understandable from technological, process and economic aspect. Our long term physical world case study reveal an actual way of building the CBM of elevators worldwide. Incorporating Internet of things and other modern technology will improve the safety and authenticity of elevator equipment,longer service life, minimize disruption or difficulty and business interference as a result of equipment downtime and to eliminate major repairs, thus result in low maintenance cost. A key contribution in this study stand in the empiric confirmation of the advantages and difficulties of CBM through Internet of things comparative to conventional CM and TBM in the instance of elevators. The writer had faith that this study is well timed and will be worth to company working on the same research or business strategies.These are form on condition based maintenance, IOT, Time-based maintenance and Corrective maintenance.

Design, Simulation and Optimization of a Novel Transpired Tubular Solar Air Heater

In this paper, a novel tubular solar air heater is introduced. In this air heater, the hot boundary layer is drawn into the absorber tube and can provide thermal energy at moderate temperatures. Several different cases were simulated and a correlation was proposed to predict the collector’s effectiveness as a function Rayleigh number and Reynolds number. An equation was derived to find the effectiveness of this collector. Finally, a real case was studied with non-uniform solar flux distribution, as well as radiation heat loss. Good agreement was found between the results and those derived by the proposed analytical method. For different suction values, the first-law and the second-law efficiencies were calculated. Based on the exergy analysis, exergy destruction in absorption is the dominant factor that is unavoidable in low-temperature collectors. It was shown that there is an optimum suction value at which the second-law efficiency is maximized. At the optimum point, temperature rise can reach 54 K, which is hardly possible with a flat plate collector. Based on the exergy analysis, the relation between tube wall temperature and air outlet temperature in their dimensionless forms at the optimum working condition was derived, and it was shown that effectiveness at the optimum working condition is around 0.5. This means that the air temperature rise shall be half of the temperature difference between collector wall and the ambient temperatures. A high outlet temperature besides the low cost of construction and maintenance are the main advantages of this air heater. With such a high temperature rise, this type of collector can increase the use of solar energy in domestic applications.

Design of OFDM‐based two‐wire bus communication system for fire safety

SummaryIntelligent fire safety systems place higher demands on the speed and reliability of data communication between sensors, controllers, and other devices. The two‐wire bus has become a significant trend in developing fire safety communication systems because of its low cost and simple maintenance. This paper proposes a two‐wire bus communication system for fire safety based on orthogonal frequency division multiplexing (OFDM) technology. First, we introduce the low‐voltage power line channel model and conduct relevant simulations, providing the conditions for subsequent simulation work. Then, we design the system's transmission and reception schemes, provide the parameters, and introduce each technology used. Finally, we conducted system simulations based on three different channel models, and the system performance is compared among different encoding, modulation, and channel estimation methods. The simulation results show that the system designed in this paper has superior performance compared with other systems and can meet the requirements of intelligent fire safety systems for communication speed and reliability.

Experimental Test Bench In A Wave Flume For The Development Of A New Mini Morphable Wells Turbine

The aim of this research study is to perform experimental tests on a new morphable mini Wells turbine designed to operate in presence of waves with limited energy content which presents a high frequency of occurrence along the Mediterranean coasts (Corsini et al., 2010). The strengths of these mini Wells turbines are: i) extremely light rotor; ii) no need of actuators to morph the rotor blades; iii) low construction and maintenance costs; iv) capability to produce energy starting from low wave heights in the order of a few decimetres. Furthermore, the small size and low investment costs of the turbine make it particularly suitable to be installed either in existing structures, such as anti-reflective perforated caissons (often used in the Mediterranean harbors), or in devices for coastal defense from erosive phenomena located on shallow water conditions. The need to carry out experimental tests derives from the difficulty of handling in a virtual Computational Fluid Dynamics environment the huge difference in the time scale of the turbine, which spins at 1500-3000 rpm, and the wave periods, in the order of some seconds (Corsini et al., 2012; Barnabei et al., 2020). Properly designed lab tests, executed in controlled conditions with irregular sea states, are therefore mandatory to fully characterize the behavior of morphable Wells turbines to be employed in the Mediterranean Sea, and in particular to assess their self-start capability.

Cost-effective high-gain DC-DC converter for elevator drives using photovoltaic power and switched reluctance motors

Low-cost photovoltaic-powered elevators (PVPEs) have gained ever-increasing attention in the last few years for their advantages in terms of renewable energy and low maintenance costs after installation. In this paper, four high-step-up DC-DC converters for low-voltage sources such as solar photovoltaic, fuel cells, and battery banks are proposed. Their performances are evaluated in terms of optimal capability and high reliability. Among the four proposed architectures, the bootstrap converter is selected for its ability to restrict losses and other redundant parameters. The proposed converter drives the inverter-driven switched reluctance motor (SRM) assembly through a directly coupled method, which eliminates the need for battery banks while aiding in cost reduction. The prototype model is implemented, and results are validated, showing promising performance and thus being very efficacious for application to low-cost PVPEs.

Recent progress in DNA data storage based on high-throughput DNA synthesis.

DNA data storage has emerged as a solution for storing massive volumes of data by utilizing nucleic acids as a digital information medium. DNA offers exceptionally high storage density, long durability, and low maintenance costs compared to conventional storage media such as flash memory and hard disk drives. DNA data storage consists of the following steps: encoding, DNA synthesis (i.e., writing), preservation, retrieval, DNA sequencing (i.e., reading), and decoding. Out of these steps, DNA synthesis presents a bottleneck due to imperfect coupling efficiency, low throughput, and excessive use of organic solvents. Overcoming these challenges is essential to establish DNA as a viable data storage medium. In this review, we provide the overall process of DNA data storage, presenting the recent progress of each step. Next, we examine a detailed overview of DNA synthesis methods with an emphasis on their limitations. Lastly, we discuss the efforts to overcome the constraints of each method and their prospects.

Electric steelmaking process monitoring with optical emission spectroscopy – An in-depth review

Electric steelmaking plays an important role in various scenarios for environmentally friendly steelmaking where the processes must be energetically and economically feasible. As electric furnaces’ capacities and low-grade recycled material usage can be expected to increase, optimizing the process practices and flexibility becomes paramount. The high-temperature environment of electric steelmaking sets several criteria for the implemented tools, where the equipment must withstand extreme conditions, have a low maintenance need and cost, and have the capability of real-time data acquisition and analysis. Optical emission spectroscopy (OES) has been studied in laboratory furnaces and on pilot and industrial scales to provide an in situ method for electric arc furnace and ladle furnace process control. Since OES is a method that measures the properties of emitted light, the applications focus on the electric arc plasma, burners’ flames, and heat radiation from the molten bath. The optical spectra carry information on the composition, temperature, and status of the process. This in-depth review compiles the research and usage of OES as a process monitoring tool by focusing on electric arc plasma, burner flames, and molten bath radiation. Suggestions for further development of existing applications and potential new applications are discussed.

Comparison through a CFD approach of static mixers in an emulsification process

Emulsions, characterized by droplet dispersions of immiscible liquids in a continuous phase, are often found in many diverse fields of the chemical industry. The energy needed to break these droplets can be sourced from mechanical agitators in stirred tanks, active mixers like pulse-flow mixers, and ultrasonic mixers. However, static mixers serve as a convenient alternative due to their typically lower maintenance costs and increased resistance to failures. Static mixers are available in diverse shapes and dimensions, with two widely used types being the Kenics Static Mixers and the Sulzer Static Mixers. While these two static mixers have been extensively studied in the literature in terms of pressure drop and mixing efficiency, to the best of the authors’ knowledge there is no study comparing the two in emulsification processes. This work aims to compare the performance of these static mixers in the production of emulsions by employing a Computational Fluid Dynamics approach. Results showed that the Sulzer Static Mixers allow to obtain higher values of turbulent energy dissipation, which in turn leads to smaller droplet diameters.

Torque Calculation and Dynamical Response in Halbach Array Coaxial Magnetic Gears through a Novel Analytical 2D Model

Coaxial magnetic gears have piqued the interest of researchers due to their numerous benefits over mechanical gears. These include reduced noise and vibration, enhanced efficiency, lower maintenance costs, and improved backdrivability. However, their adoption in industry has been limited by drawbacks like lower torque density and slippage at high torque levels. This work presents an analytical 2D model to compute the magnetic potential in Halbach array coaxial magnetic gears for every rotational angle, geometry configuration, and magnet specifications. This model calculates the induced torques and torque ripple in both rotors using the Maxwell Stress Tensor. The results were confirmed through Finite Element Analysis (FEA). Unlike FEA, this analytical model directly produces harmonics values, leading to faster computational times as it avoids torque calculations at each time step. In a case study, a standard coaxial magnetic gear was compared to one with a Halbach array, revealing a 14.3% improvement in torque density and a minor reduction in harmonics that cause torque ripple. Additionally, a case study was conducted to examine slippage in both standard and Halbach array gears during transient operations. The Halbach array coaxial magnetic gear demonstrated a 13.5% lower transmission error than its standard counterpart.

Dynamic probability modeling-based inspection intervals optimization for civil aircraft composite structures using Bayesian updating

The evaluation of damage tolerance in composite materials is essential for ensuring the safety of aircraft structures. One of the most challenging aspects of applying probability modeling-based methods to evaluate damage tolerance is determining the actual damage size distributions for in-service aircraft structures. Although existing nondeterministic approaches have been used to optimize inspection intervals of composite structures, few studies have investigated the effects of updates on the actual damage size distribution and its impact on both the probability of structural failure and inspection intervals. This paper proposes a dynamic optimization method for inspection intervals of composite structures based on Bayesian updating. The damage size distribution of the composite structure is characterized by a general stochastic distribution. A Bayesian updating methodology is presented to iteratively update the actual damage size distribution whenever new data becomes available. Based on the constructed probability model, the inspection intervals of composite structures are determined under the objectives of optimal safety and economy for civil aircraft using a Monte Carlo approach. Compared to prior distribution models, the proposed method achieves higher safety for structures during a single inspection, reduces the failure probability of structures throughout their entire service life, and incurs lower maintenance costs. It also enables maintenance personnel to flexibly adjust inspection intervals while facilitating quantitative evaluation of both failure probabilities and maintenance costs associated with these intervals. These findings suggest that the proposed method holds great potential in enabling maintenance personnel to make informed decisions regarding inspection intervals for improved safety and economic performance.

Evaluation of mechanical properties of paver blocks by replacing cement with fly ash and marble waste

Paver blocks (PB) play a pivotal role in various construction and infrastructure works providing aesthetically and durable pleasing surfaces for various applications such as pavements, walkways, and driveways. These blocks can be used for heavy vehicle loads instead of low-strength clay bricks and tiles. PB gained focus in the construction industry due to its multi-advantages like high strength, durability, and low maintenance cost. However, due to the usage of cement, its application is limited, which releases a huge amount of carbon dioxide into the ecosystem. Thus, it leads to global warming and climate change. In addition, cement is one of the expensive materials used in PB, which further reduces the interest of the construction industry and end-users of PB. Marble waste as its excessive amount of generation from stones in industry and fly ash as a byproduct from coal combustion immediate opportunities to use these materials and reduce the impact of waste material on the environment. Therefore, this study aims to reduce cement consumption by partially replacing marble waste and fly ash combinedly. The study contributes practically to the use of alternative materials in the construction industry. Three types of samples namely M1 (replacement with marble waste), M2 (replacement with fly ash), and M3 (replacement with both fly ash and marble waste) were used. Various proportions were added as a partial replacement, the replacement varying from 5 to 30%, which was 5%, 10%, 15%, 20%, 25%, and 30%. Statistical analyses were carried out for interpretations of the data. The result concluded that all three mixes achieved their maximum compressive strength on different days of curing. M1-15 and M3-20 mixes achieved maximum compressive strength related to control specimens at 56 days. However, the M2-20 mix achieved maximum compressive strength at 7, 28, and 56 days, The maximum flexural strength was recorded by the M1–15 mix at 7 and 56 days, while the M2–20 and M3–20 mix achieved maximum flexural strength at 7, 28 and 56 days. ANOVA tests by one-way indicate that there is no difference in the mean of compressive strength however, there is a difference in the mean of flexural strength. The Tukey post hoc analysis shows a statistically significant difference between all levels of days of compressive and flexural strength, except for some levels of compressive strength. The correlation test results indicate a positive and strong association between all three mixes.

Inspection of microwave self‐healing efficiency in carbon nanotube reinforced polymer composites for aerospace applications

AbstractThe aerospace industry is evolving very rapidly every day, and due to the low operational and maintenance costs, unmanned aerial vehicles (UAVs) are utilized for many duties, including imaging, patrol, surveillance, and delivery. Flying platforms prioritize effective load‐carrying capacity and light weight. To achieve this, lightweight materials with sufficient strength are utilized, and design optimizations are implemented. This study investigates material development for a UAV propeller, taking into account the possible consequences of a bird strike or hard landing such as micro damage occurrence. In this study, a twin‐screw extruder was used to produce hybrid composites by blending a thermoplastic, polyamide‐6 (PA6) with olefin block copolymers (OBC) and carbon nanotubes (CNT). After manufacturing test specimens by injection molding, tensile and Charpy impact tests were performed. OBC increased the elongation capacity and impact resistance of the PA6 through maleic anhydride (MAH) grafting while reducing the tensile strength. CNT incorporation compensated for this drop, but it rendered the composites more brittle. More importantly, due to the CNT's microwave (MW) absorption capacity, the hybrid composites have gained self‐healing properties. Extended MW exposure time and high MW powers may cause localized burning of the material, resulting in a decrease in its self‐healing efficiency. Following the failure of the examined composites, SEM microscopy revealed various toughening mechanisms in the composites. The use of a modified Halpin‐Tsai model to estimate the elastic characteristics of CNT‐reinforced composites revealed promising results, with minimal discrepancies when compared to experimental data.Highlights CNTs were found efficient for the self‐healing behavior which is critical for improving the lifetime and planning maintenance for UAV propellers. CNT content, MW power & exposure time all impact the self‐healing efficiency. Extended MW exposure time and high MW powers can cause localized burning of the material, resulting in a decrease in its self‐healing efficiency. CNTs created bridge effects, ultimately leading to an enhancement in the strength of the composites. The use of a modified Halpin‐Tsai model yielded good accuracy with experimental data.

Spirulina (Arthrospira platensis) supplementation: Impact on growth, metabolism, and antioxidant status in zebrafish

AbstractZebrafish (Danio rerio) is a valuable model for biomedical research because of its mammalian genetic similarities, rapid reproduction, and low maintenance costs. However, further investigation is required regarding their nutritional requirements and standardized laboratory diets. This study evaluated the metabolic and growth responses of zebrafish juveniles fed on diets supplemented with spirulina, Arthrospira platensis (SP) at different levels for 77 days. Six diets with SP inclusion levels of 0%, 2%, 4%, 6%, 8%, and 10% (SP0‐SP10) were formulated. A total of 300 zebrafish juveniles with an average initial weight of 0.113 ± 0.10 g (mean ± SD) were randomly distributed across six groups, with five replicates per group, each containing 10 animals. After 77 days, the SP6 group demonstrated significantly enhanced growth performance compared with the other supplementation levels. The condition factor was markedly higher in the SP6 and SP8 groups than in the SP0 group. No significant effects on total cholesterol levels were observed, but the SP4, SP6, and SP10 diets decreased triglyceride levels. Lipase activity was higher in the SP6 and SP8 groups than in the control group, whereas amylase activity showed no significant differences between treatments. Catalase and superoxide dismutase activities were significantly higher in the SP8 and SP10 groups than in the SP0 and SP2 groups. Glutathione S‐transferase activity was higher in the SP6, SP8, and SP10 groups than in the SP0 group. In addition, SP inclusion in zebrafish diets improved female gonadal development. In conclusion, this study indicates that SP supplementation has substantial potential as a growth promoter, positively influencing lipid metabolism and antioxidant enzyme activity without affecting zebrafish survival.

State of the Art of Modelling and Design Approaches for Ejectors in Proton Exchange Membrane Fuel Cell

Proton exchange membrane fuel cell (PEMFC) has a promising future in the power generation and transportation fields. Recirculation of unused anodic gases is fundamental to achieve a high-performance energy system, and this is usually attained employing ejectors or pumps. With respect to the latter, ejectors present no moving parts, thus resulting in both higher overall efficiency of the system and lower maintenance cost. Their main drawback is represented by the narrow optimal operative range: the entrainment ratio (ER) greatly depends on primary pressure, working pressure, and operative condition in general. In the last decade, numerous authors focused their efforts on fully comprehending and correctly simulating their working principles and analyzing how geometrical parameters influence ER and design different geometries to enlarge the operative range. The aim of this paper is to present in an ordered and clear manner the state of the art of ejector design, both from simulative (turbulence model, single or multiphase stream, etc.) and empirical (commonly used “rule of thumb”) points of view.