Low Maintenance Costs Research Articles

High cell density culture of Neochloris oleoabundans in novel horizontal thin-layer algal reactor: Effects of localized aeration, nitrate concentration and mixing frequency

A horizontal thin-layer algal reactor was designed, constructed and tested for high cell density culture of an oil-rich green alga, Neochloris oleoabundans, at a thickness of 6 mm. A hollow fiber membrane sparger was used for localized aeration with CO2-enriched air, which allowed control of culture pH at a narrow range of pH 7.0–7.5. The optimal nitrate concentration under the investigated conditions was 345 mg-N/L with a cell density of ∼6.6 × 108 cells/mL and biomass concentration of ∼8 g/L. The volumetric and areal biomass productivities were 1.81 g/L/day and 10.85 g m− 2/day, respectively, and the maximum volumetric and areal productivities 3.57 g/L/day and 21.42 g m− 2/day, respectively. Intermittent mixing at a frequency of once every two hours (five min mixing each time) produced a cell growth profile similar to that of continuous mixing. Such intermittent mixing resulted in 98.38 % saving on mixing energy and 33.9 % reduction in water evaporation. It was observed that metabolic stress such as high pH and high nitrate concentration could inhibit cell division while causing cell size to enlarge abnormally. The results indicate that it is technically feasible to have high cell density culture of photoautotrophic microalgae with intermittent mixing and no culture circulation, opening the door towards the development of open algal farming systems of low capital, operational, and maintenance costs.

Current and Future Trends for Crude Glycerol Upgrading to High Value-Added Products

Crude glycerol is the main byproduct of biodiesel manufacturing from oleaginous crops and other biomass-derived oils. Approximately 10% crude glycerol is produced with every batch of biodiesel. Worldwide, there is a glut of glycerol and the price of it has decreased considerably. There are real opportunities for valorizing crude glycerol into higher value-added chemicals which can improve the economic viability of biodiesel production as an alternative fuel. Exploring new potential applications of glycerol in various sectors is needed such as in pharmaceuticals, food and beverages, cosmetics, and as a transportation fuel. However, crude glycerol produced directly from biodiesel often contains impurities that hinder its direct industrial usage and thus, a refining process is needed which is typically expensive. Hence, this review reports on current upgrading crude glycerol technologies—thermo-, bio-, physico-, and electrochemical approaches—that valorize it into higher value-added chemicals. Through comparison between those viable upgrading techniques, future research directions, challenges, and advantages/disadvantage of the technologies are described. Electrochemical technology, which is still underdeveloped in this field, is highlighted, due to its simplicity, low maintenance cost, and it working in ambient condition, as it shows promising potential to be applied as a major glycerol upgrading technique.

A Novel Approach Using High Charging Voltage for the Restoration of Discarded Lead Acid Batteries

A lead acid battery is an old renewable battery that is usually discharged to deliver a high surge current to ignite a petrol-based engine. Nowadays, there are different improved versions of lead acid batteries that can deliver high energy densities with low maintenance costs. As the batteries are charged and discharged repeatedly over time, the amount of lead sulfate across the electrode plates grows, reducing the total surface areas of the plates and, thus, the rate of ionization between the electrolyte and the plate surfaces. The batteries then eventually come to the end of their service lives. Even with the improved versions, lead acid batteries are usually discarded at their retirement. However, if the retired batteries can be used for other purposes, the circular economy of the batteries can be improved significantly. It is therefore necessary to study the physical characteristics of the retired batteries and explore means of improving their charging and discharging capabilities. This paper presents research on improving the storage capability of retired lead acid batteries by applying different charging voltages across them. The results show that the electrode plates of the retired batteries become porous when a high charging voltage is applied, hence increasing the total surface area of the plate surfaces. The storage capability of the batteries is improved because the accumulated lead sulfate is removed from the electrode plates by the high charging voltage. As a result, the rate of ionization is increased, hence restoring the storing capability of the retired batteries to up to 71–89% of the original capacity rating.

Multi-Hazard Effects of Crosswinds on Cascading Failures of Conventional and Interspersed Railway Tracks Exposed to Ballast Washaway and Moving Train Loads.

The interspersed railway track is an enhanced timber railway track, spot-replacing damaged wooden sleepers with new concrete sleepers to improve the bearing capacity of existing railway lines. Although this interspersed solution is characterised by low cost and short maintenance time, the interspersed tracks have worse stability than concrete tracks and can deteriorate quickly when exposed to extreme weather conditions such as heavy rains and floods. In many cases, heavy rains and floods are accompanied by strong winds. Ballast washaway can often be observed under flood conditions while the mass of trains is unevenly distributed on two rails due to the effect of lateral wind load and rail irregularities. The current work is the first in the world to investigate the collective multi-hazard effects of ballast washway and uneven axle loads on the vulnerability of conventional and interspersed railway tracks using nonlinear FEM software, STRAND 7. The train bogie is modelled by two sets of point loads. The maximum displacement, bending moment and twists have been studied to evaluate the worst condition. The novel insights will help the railway industry develop proper operations of interspersed railway tracks against naturally hazardous conditions.

Parametric assessment of a Pelton turbine within a rainwater harvesting system for micro hydro-power generation in urban zones

Hydroelectric power is a renewable and sustainable approach in energy production. However, hydro power generation is almost exclusively used at large scale (>10 kW). On a micro scale, it is still being assessed as a viable alternative to produce energy, even though this generation process seems to require lower installation and maintenance costs. The main aim of this work is the performance assessment of a micro hydro power station integrated into a rainwater harvesting system based on the optimal dimensioning of the turbine geometry. This project proposes different hydraulic heads for a sustainable model that uses the potential energy to generate electrical power in urban areas. As case of study, the system was set up for an industrial facility in the Toluca Metropolitan Zone, Mexico. A methodology was developed in order to: a) determine hydraulic setting-up based on the precipitation regime and operational requirements of the generator; b) assess an efficiency indicator under size variation of main geometric elements through Computational Fluid Dynamic (CFD); and c) validate the prototype throughout a 3D model. Due to the nature of the rainwater harvesting system, the type of the turbine selected was a Pelton turbine. Afterwards, hydraulic characteristics were defined, such as initial size of turbine, as well as the number and diameter of conduit pipes, nozzles, valves, and gates. Besides, the fluid behavior (velocity and pressure fields) in the turbine was analyzed by CFD to define a suitable geometry. Numerical modeling of the turbine allowed to estimate expected system efficiency according to the variation of a coefficient based on inlet and outlet velocities w2w1. By means of an electronic circuit, which measured number of revolutions per minute and power generation (voltage and electrical current) of the system, efficiency and energy produced by the system were analyzed under both controlled conditions and real-time rainfall conditions. In general, the hydro power station managed to generate electrical energy using rainwater harvesting system which achieved up to 81.13% of efficiency.

A New Wave Energy Converter for Marine Data Buoy

Providing stable and reliable power supply for offshore equipment with special power requirements, such as marine data platforms and marine buoys far away from the coast is currently topical research issue. At present, most of these devices use photovoltaic power generation or install high-capacity batteries and carry out regular replacement of electricity supply schemes. Due to the high dependence of photovoltaic power generation on solar radiation and the high cost arising from frequent battery replacements, wave energy is considered as a solution. Wave energy converters (WECs) are devices that convert the energy stored in waves into electrical energy, and its main advantage is the sustainable supply of electricity. In this article, a new built-in wave energy converter with high reliability and low maintenance costs is proposed and investigated for marine data buoys. Its core is a direct-drive energy conversion unit based on a magnetic lead screw design. The device can passively follow the pitching state of the buoy under the impact of waves to maximize its power generation. The proposed WEC is introduced and investigated through model analysis and prototype experiments. The experimental results confirm the power generation performance of a 50 kg power generation prototype and show the advantages of the proposed device.

Living membrane bioreactor for highly effective and eco-friendly treatment of textile wastewater

The treatability of synthetic textile wastewater containing model dyes, such as reactive black and direct black dye (25.0 ± 2.6 mgdye/L), with chemical oxygen demand (COD, 1000 ± 113 mg/L), ammonia‑nitrogen (NH3-N, 140 ± 97 mg/L) and sulphate ions (SO₄2−, 1357 ± 10.86 mg/L) was investigated in this study using an innovative living membrane bioreactor (LMBR) using an encapsulated self-forming dynamic membrane (ESFDM). The key advantage of ESFDMBR is the self-forming of the biological filtering layer protected between two meshes of inert robust and inexpensive material. A laboratory scale bioreactor (BR) equipped with a filtering unit mounting polyester meshes with a pore size of 30 μm, operated at an influent flux of 30 LMH was thus used. After the formation of the biological living membrane (LM), the treatment significantly reduced COD and DOC concentrations to the average values of 34 ± 10 mg/L and 32 ± 7 mg/L, corresponding to reduction efficiencies of 96.0 ± 1.1 % and 94 ± 1.05 %, respectively. Throughout the LMBR operation, the colours were successfully removed from synthetic textile wastewater with an overall removal efficiency of about 85.0 ± 1.8 and 86.0 ± 1.9 % for direct and reactive dyes, respectively. In addition, the proposed system was also found effective in affording removal efficiency of ammonia (NH3) of 97 ± 0.5 %. Finally, this treatment afforded circa 40.7 ± 5.8 % sulphate removal, with a final concentration value of 805 ± 78.61 mg/L. The innovative living membrane, based on an encapsulated self-forming dynamic membrane allows a prolonged containment of the membrane fouling, confirmed by investigating the concentration of membrane fouling precursors and the time-course variations of turbidity and transmembrane pressure (TMP). Those final concentrations of wastewater pollutants were found to be below the limits for admission of the effluents in public sanitation networks in Italy and Tunisia, as representative countries for the regulation in force in Europe and North Africa. In conclusion, due to the low costs of plant and maintenance, the simple applicability, the rapid online implementation, the application of LMBR results in a promising method for the treatment of textile wastewater.

Investigation of moss species selection and substrate for extensive green roofs

This study investigates the potential of moss species for extensive green roofs to achieve very shallow substrate, low maintenance and low cost green roofs. The performance of four moss species (Didymodon constrictus, Eurhynchium hians, Polytrichum commune and Racomitrium japonicum) were assessed using three kinds of substrate: (a) a mixture of clay soil and compost, b) baked black soil and c) river sand for two years in Chiba, within the Tokyo region of Japan. The individual species were grown in monoculture in 4 cm depth of substrate in trays on a rooftop without supplemental irrigation using an onsite propagation method. Although all four species became dormant in conditions of high temperature and little rain, it was possible for all to establish and survive. R. japonicum showed the greatest coverage among the four species, reaching 70%–80% cover in the first four months. P. commune performed almost as well but took over a year to reach consistently high coverage. E. hians coverage fluctuated greatly in response to drought events. D. constrictus had low coverage overall but grew slightly more in the clay/compost soil; P. commune did poorly in sand substrate; R. japonicum and E. hians showed no consistent differences in how they were affected by substrate type. After two years only R. japonicum and P. commune had high enough coverage to consider further investigation. R. japonicum is already used in green roofing and wall applications. This study suggests that while some mosses show high performance across substrate types, others can be used on green roofs to achieve high cover, but only after determining a suitable substrate type. These results can inform moss species selection for green roofs in Japan, however, this methodology can be applied in other regions to establish moss green roofs. An onsite propagation method can be used to establish moss green roofs but further research is needed to identify means of increasing onsite growth rates for more species.

Tropospheric Delay Calibration System Performance During the First Two BepiColombo Solar Conjunctions

AbstractMedia propagation delay and delay‐rate induced by the water vapor within the Earth's troposphere represent one of the main error sources for radiometric measurements in deep space. In preparation for the BepiColombo and JUICE missions, the European Space Agency has installed and operates the prototype of a tropospheric delay calibration system (TDCS) at the DSA‐3 ground station located in Malargüe, Argentina. An initial characterization of the TDCS performance was realized using two‐way Doppler measurements at X‐band to perform the orbit determination of the Gaia spacecraft. This work will further characterize the system by analyzing two‐way Doppler and range data at X‐ and Ka‐band for 31 tracking passes of the BepiColombo spacecraft, which were recorded between March 2021 and February 2022 during the first two solar conjunction experiments. The performance exceeds the expectations based on the previous analysis, with a reduction of the Doppler noise of 51% on average and up to 73% when using the TDCS measurements in place of standard calibrations based on global navigation satellite system data. Furthermore, the campaign serves as validation of the TDCS operations during superior solar conjunctions, with most of the tracking passes at low elongation now satisfying the Mercury orbiter radioscience experiment requirements on two‐way Doppler stability. These results, which are in line with those of similar instruments installed at other Deep Space Network antennas, are obtained using a commercial microwave radiometer with significantly lower installation and maintenance costs.

Performance Comparison of Straight, Curved, and Tilted Blades of Pico Scaled Vortex Turbine

In the 26th Conference of the Parties (COP26), United Nations Framework Convention is committed to suppressing the acceleration of climate change due to carbon by applying energy from fossil fuels to New Renewable Energy (NRE). Indonesia targets that in 2060 the coal phase-out will be replaced by renewable energy 2056. As a tropical country with many rivers and many lakes, Indonesia has a water energy potential of 75,000 MW. In some remote areas, the need for electrical power is pico scaled (< 5kW). The vortex turbine was chosen to be suitable for river flow with low water levels, low maintenance and construction costs, as well as being environmentally friendly for the underwater ecosystem. This study aims to compare the performance of the vortex to the differences in the shape of the pico scale blade. This study was carried out with variations in the shape of the straight, tilted, and curved blades. Based on the results of all vortex turbine studies, it can be ascertained that the best blade shape obtained numerically is an inclined blade with a hydraulic efficiency of 36%.

Research on Fault Diagnosis of Wind Turbine Gearbox with Snowflake Graph and Deep Learning Algorithm

Wind power generation is one of the important development projects for renewable energy worldwide. As wind turbines operate in harsh environments, failure of the wind turbines often occurs, thus leading to lower power generation efficiency and high maintenance cost. Earlier detection of the fault type can reduce the maintenance cost. This study proposed a hybrid recognition algorithm based on the symmetrized dot pattern (SDP) and convolutional neural network (CNN) for wind turbine gearbox fault diagnoses. In addition to a fault-free type, four fault types were discussed in this paper, including gear rustiness, broken tooth, wear, and aging. A vibration sensor was used for measurement. The original vibration signals of the gearbox were captured by a NI-9234 high-speed data acquisition card, filtered by a fast Fourier transform, and imported into the SDP to create the snowflake image features. Afterward, CNN diagnosed the gearbox fault type. There were 1500 test data in this study. A total of 200 data items for each fault type were used as training samples, and 100 data of each type were used as test samples. The test result shows that the training accuracy was 98.8%. The proposed method can diagnose the fault condition of the gearbox effectively and identify the fault type of the gearbox accurately. This is favorable for the quick maintenance of wind turbines.

Diet supplementation with egg yolk powder fattens the beetle Tribolium castaneum.

Insects have become essential models in studying human metabolic diseases, mainly due to their low maintenance cost and available tools. Both mutations and modified diets induce metabolic states similar to human obesity and diabetes. Here, we explore the effect of a high-calorie, high-fat diet on the metabolism of the beetle Tribolium castaneum. Supplementation of the wheat flour diet with powdered egg yolk for 3 weeks increased the total triacylglycerol and accelerated larval development. In addition, this diet increased the triacylglycerol levels of adult beetles. However, this egg yolk supplementation did not alter the larvae's total glucose levels or lipogenic capacity and ATP citrate lyase activity. The diet also did not change the expression profile of several lipid and carbohydrate metabolism genes and insulin-like peptides. Thus, we conclude that the diet supplemented with egg yolk induces increased fat without causing diabetes phenotypes, as seen in other hypercaloric diets in insects.

A Multi-Criteria Analysis on Solar and Traditional Technologies in Irrigation Development

The main aim of this study is to conduct an economic analysis and a multi-criteria analysis of electric, diesel, and solar irrigation pumps to find the best irrigation technology. After collecting the necessary data, a cost comparison is made between solar and conventional irrigation technologies. The cost of each technology is then compared using a 25-year lifespan to determine which one will be less expensive. Since there are additional important factors to consider while selecting the optimal technology, a multi-criteria analysis is done too. The cost comparison reveals that, in contrast to the other two, the solar system has higher startup expenditures but lower ongoing operating and maintenance costs. According to the cost analysis of the three technologies, solar technology is significantly less expensive than electric and diesel alternatives. Aside from the cost, electric irrigation technology appears to be a better option than solar and diesel technologies when considering other aspects like farmer satisfaction, necessary installation land, technology accessibility, weather obstruction, etc. Journal of Engineering Science 13(2), 2022, 101-110

Systematic identification of smORFs in domestic silkworm (Bombyx mori).

The silkworm (Bombyx mori) is not only an excellent model species, but also an important agricultural economic insect. Taking it as the research object, its advantages of low maintenance cost and no biohazard risks are considered. Small open reading frames (smORFs) are an important class of genomic elements that can produce bioactive peptides. However, the smORFs in silkworm had been poorly identified and studied. To further study the smORFs in silkworm, systematic genome-wide identification is essential. Here, we identified and analyzed smORFs in the silkworm using comprehensive methods. Our results showed that at least 738 highly reliable smORFs were found in B. mori and that 34,401 possible smORFs were partially supported. We also identified some differentially expressed and tissue-specific-expressed smORFs, which may be closely related to the characteristics and functions of the tissues. This article provides a basis for subsequent research on smORFs in silkworm, and also hopes to provide a reference point for future research methods for smORFs in other species.

Mobile technology as a dependable alternative to language labs and to improve listening skills

There is an incessant gap between language acquisition and adoption of modern technologies, especially in semi-urban parts of economically growing countries in Asia. There is a need to establish infrastructure for Computer Assisted Language Learning (CALL), Information Communication Technology (ICT), Virtual Reality (VR), and Augmented Reality (AR) to enrich English Language Teaching. Though these types of establishments instil confidence and fluency among English learners, investment in procurement, running costs towards maintenance and service cost deter institutions from establishing Language Labs and Language studios. The objective of this study was to establish Mobile-Assisted Language Learning (MALL) in higher education institutions and enhance English fluency and accuracy with minimal operation and low maintenance cost. The study also methodologically shortlisted open-source mobile applications based on users' feedback on their user-friendliness, skill-levels, content, and options that promote Learners' Autonomy. A quantitative true-experimental study was conducted at the Vellore Institute of Technology, Vellore, India, to develop the listening skills of (n=121) students of first-year Bachelor of Technology in a varied branch. The pre-test and post-test results revealed improvements in the experimental group. The findings would immensely help the underprivileged to serve ESL learners from any part of the globe who intend to enhance their proficiency in English.

An Evaluation of the Efficiency of the Floating Solar Panels in the Western Black Sea and the Razim-Sinoe Lagunar System

The development of novel solar power technologies is regarded as one of the essential solutions to meeting the world’s rising energy demand. Floating photovoltaic panels (FPV) have several advantages over land-based installations, including faster deployment, lower maintenance costs, and increased efficiency. Romania is considered a country with enormous solar energy potential, which is one of the most exploited sectors of the renewable energy sector. With this in mind, the purpose of this work is to assess the energetic potential provided by the sun, taking into account three lakes in Romania’s east and extending to the west of the Black Sea. In this context, we examine the hourly distribution of solar radiation for the year 2021. The solar radiation data were extracted using the ERA5 database, as well as data collected in situ near them. Following this research, we discovered that all of the chosen locations have a high energetic potential and could be used as locations for the exploitation of solar energy, thereby avoiding the use of land that could be used for agricultural purposes in these areas. We also noticed that there are minor differences between the solar radiation values obtained from the ERA5 database and the measured ones.

Design and Fabrication of Solar Powered Tiller with Seed Sowing

Agriculture is very important for the Indian economy. India being a developed nation, where agriculture plays a major role in developing the nation needs in all outcomes, The present project aims to develop Solar Powered tiller to reduce the time of the farmer by digging into the soil for multiple times in a certain area, where it’s having an attachment of seed sowing. The chain sprocket is a motorized by wiper motor and tiller blade will break the soil into small pieces, which helps improve the aeration of soil and prevents weeds from growing. Here the power to accelerate the equipment is utilized from the solar panel and stored in the battery for further purpose, where the panel is fixed at the top of the tiller for continuous rays of energy absorption. The multimeter is fixed to check the solar panel output voltage. By using the power, it tends to run the tiller in a proper manner. The seed sowing hopper is fixed at back side of wheel, where the seeds are flow in ground by reciprocating motion by means of rotating wiper motor. Now this project's major focus is on creating a functional operating system. High safety reduced human effort, improved soil tiller efficiency, decreased work load, less worker fatigue, and lower maintenance costs are all achieved by the project.

Effect of construction technology on air-lifting pump mining

The air-lifting pump has the advantages of low cost, strong reliability, simple structure and convenient maintenance, especially in the fields of deep-sea mining, oilfield mining and mineral mining under complex geological conditions. The construction technology and air intake mode not only play a decisive role in the performance of the air-lifting pump, but also greatly hinder the engineering application of the air-lifting pump. Here, the air-lifting pump is taken as the research object, and the river sand is used as the experimental transport medium. The particle concentration-efficiency model is established based on the mechanical energy conservation theorem. The working performance characteristic parameters of the air-lifting pump under different construction technologies are obtained by a three-axis motion control system. On this basis, the working performance characteristic parameters of the air-lifting pump under different intake modes are obtained by changing the intake mode. The results show that the particle concentration-efficiency model can well describe the efficiency of lifting solid particles by the air-lifting pump. When the sand depth is less than 200 mm, the concentration and efficiency of solid particles transported by the air-lifting pump in the horizontal movement construction are significantly better than those in the fixed position construction. In the same construction technology, the solid particle concentration of the air-lifting pump in uniform intake mode is better than that in non-uniform intake mode, while the transportation efficiency of the air-lifting pump in non-uniform intake mode is better than that in uniform intake mode. The research results of this paper can provide an important theoretical reference value for the air-lifting pump in practical engineering applications.

Optimal Integration of Photovoltaic Systems in Distribution Networks from a Technical, Financial, and Environmental Perspective

Due to the increasing demand for electricity around the world, different technologies have been developed to ensure the sustainability of each and every process involved in its production, transmission, and consumption. In addition to ensuring energy sustainability, these technologies seek to improve some of the characteristics of power systems and, in doing so, make them efficient from a financial, technical, and environmental perspective. In particular, solar photovoltaic (PV) technology is one of the power generation technologies that has had the most influence and development in recent years due to its easy implementation and low maintenance costs. Additionally, since PV systems can be located close to the load, power losses during distribution and transmission can be significantly reduced. However, in order to maximize the financial, technical, and environmental variables involved in the operation of an electrical system, a PV power generation project must guarantee the proper location and sizing of the generation sources. In the specialized literature, different studies have employed mathematical methods to determine the optimal location and size of generation sources. These methods model the operation of electrical systems and provide potential analysis scenarios following the deployment of solar PV units. The majority of such studies, however, do not assess the quality and repeatability of the solutions in short processing times. In light of this, the purpose of this study is to review the literature and contributions made in the field.

Study on the Power Data Assets and Trading System Design of Blockchain

The sensitive data such as electric power data suffer from the easily abuse in the traditional centralized data trading system. To solve this problem, the blockchain-based power data’s capitalization and trading system were proposed in this study. Given the trust for blockchain technology, this work established a multi-party trusty network between multiple parties in the distributed ledger with cryptographic algorithms, and distributed multi-party consensus protocol. The system development with Hyperledger’s consortium blockchain framework Fabric made the power data safe, transparent and immutable. The local development environment for testing included a operating system MAC OS 10.14.6, six-core CPU 3.0 GHz, RAM 16 GB. A single machine is configured with multiple block chain network nodes, an ordering node, and two organizations Org0 and Org1, each of which has two nodes Peer0 and Peer1, and adopts the Solo consensus mechanism. The experimental results show that the system run well in the integrated test, satisfied the design requirements, and had low maintenance costs and improved security. Compared with the traditional data trading system, the blockchain-based power data’s capitalization and trading system demonstrated the comprehensive functionality and security advantages in the study.