Engineering reports : open access最新文献

Sarcosine was inserted between fatty chain and carboxylic group of lauric acid to obtain lauroyl sarcosine, and the corrosion inhibition of lauroyl sarcosine triethanolamine (LSTEA) was significantly improved. The synergistic mechanism of amide group and lauric acid was investigated by comparing the corrosion behavior on the surface of HT300 gray cast iron in 330 mg/L NaCl solution. The results showed that both lauryl triethanolamine (LATEA) and LSTEA could prevent corrosion. At 298 K, when 1000 mg/L inhibitor was added, the inhibition rates are 71.93% and 83.89%, respectively. The morphology analysis also verified that LSTEA had better inhibition properties than LATEA. Comparing the adsorption parameters and Density Functional Theory (DFT) calculation results, it was found that LATEA and LSTEA could spontaneously adsorb on the surface of gray cast iron as monolayer to form a stable protective layer. However, the chelation of amide group and the electron absorption effect could make the electron density distributed at the polar end of the whole molecule, covering the active sites at the interface to the maximum extent, so that LSTEA has more excellent corrosion inhibition for gray cast iron.

The problem of non-uniform voltage distribution in the internal element of metallized film capacitors in flexible HVDC transmission systems exists, the influence of electrical parameters of dielectric and metal copper row are not considered in the existing metallized film capacitor equivalent circuit model. In this paper, the conductance of biaxially oriented polypropylene film (BOPP) for metalized film capacitors is measured at different electric field intensity and dielectric properties at different frequencies. The current density distribution and voltammetric properties of the metalized film capacitor elements under AC and DC superimposed voltages are calculated by the finite element method, and the voltammetric properties of the copper row considering the skin effect are derived. The equivalent circuit model of the metalized film capacitor under the AC-DC superposition voltage is proposed. The simulation results of the capacitor equivalent circuit model show that the voltage distribution of the internal elements of the capacitor is uniform at low frequency AC voltages (<10² Hz), and the voltage amplitude and phase difference between the elements of the capacitor gradually increases with increasing AC voltage frequency. At an AC voltage frequency of 10⁵ Hz, the difference in magnitude between the two capacitor elements on the same copper row was up to 2.01% and the phase difference was 13.5%, while the difference in magnitude between capacitors at the same horizontal position on different copper rows was up to 56.8% and the phase difference was 10.44%. The results of this paper provide some guidance for the modeling of the internal components of metalized film capacitors, the calculation of voltage distribution and the structural optimization design.

Wireless body area networks (WBAN) provide remote services for patient monitoring which allows healthcare practitioners to diagnose, monitor, and prescribe them without their physical presence. To address the shortcomings of WBAN, software-defined networking (SDN) is regarded as an effective approach in this prototype. However, integrating SDN into WBAN presents several challenges in terms of safe data exchange, architectural framework, and resource efficiency. Because energy expenses account for a considerable portion of network expenditures, energy efficiency has to turn out to be a crucial design criterion for modern networking methods. However, creating energy-efficient systems is difficult because they must balance energy efficiency with network performance. In this article, the energy efficiency features are discussed that can widely be used in the software-defined wireless body area network (SDWBAN). A comprehensive survey has been carried out for various modern energy efficiency models based on routing algorithms, optimization models, secure data delivery, and traffic management. A comparative assessment of all the models has also been carried out for various parameters. Furthermore, we explore important concerns and future work in SDWBAN energy efficiency.

Dry ice is one of the world's most in-demand commodities for cold chain distribution of temperature sensitive products in insulated shippers. A commonly used rule of thumb is that dry ice sublimates about 8% every 24 h, without consideration for dry ice type, size, or geometry. This study explored sublimation rates of dry ice composition (binding agent and density), age, and geometry (size and shape). Dry ice block manufacturing often involves dosing propylene glycol-water “binder” solution to liquid carbon dioxide. Tests performed in this study revealed that the binding agent did not influence the dry ice sublimation rate. Dry ice density was found to impact sublimation rate. Fresh and aged blocks of similar dimensions and mass were found to have similar performance outcomes. Mass loss curves for pellets and various sized dry ice blocks showed a dependence on surface area and volume. Chunked blocks and pellets with and without binding agent sublimated at similar rates of 2.84 and 2.53% h⁻¹ (w/w), respectively, whereas block varieties with significantly lower surface area to volume ratios had lower sublimation rates of 0.98–1.60% h⁻¹.

Today's industries need to be more productive, especially those that shape and machine materials. As a result, engineers and scientists are seeking for cutting tool materials and technologies that have high hot hardness, chemical stability, wear resistance, and toughness while also improving tool life or contact time. Cryogenic treatment of cutting tools has been proven to be a good way for increasing the contact time of any cutting tool material. This study presents the results of turning alloy steel (EN24 grade) using P20 grade carbide inserts under various conditions under continuous machining. Cutting speeds varied from 100 to 500 m/min (in increments of 100 m/min), with feed rates ranging from 0.1 to 0.4 mm/rev in stages of 0.1 mm/rev and a constant radial depth of cut of 1.5 mm were considered under dry machining conditions. Cryogenic treated/coated inserts are better than other inserts in terms of tool life for optimized parameters such as cutting speed 100 m/min, feed rate 0.1 mm/rev, and depth of cut 1.5 mm, according to the study's findings. Under similar conditions of cutting speed, feed rate, and depth of cut, coated/cryotreated inserts had a tool life increase of about 97.5% over uncoated/untreated inserts, a 50.58% increase over uncoated/crytreated inserts, and a 23.89% increase over coated and untreated inserts, respectively.

Online social networks (OSNs) have reduced global boundaries, with Twitter enabling perspective sharing. Bot profile-propagated false information misuse raises serious concerns. Considering this issue, we present our research on classifying Twitter accounts as “human” or “bot” using deep neural networks and transfer learning. Our proposed approach, TL-PBot, stands for bot profile detection using transfer learning. The TL-PBot framework utilizes Twitter account metadata such as follower count. Our TL-PBot also incorporates text data from the Twitter description field as a feature. Word representation of the text data is achieved using Global Vectors (GloVe), a pre-trained model. By employing user profile-based features, we significantly reduce the overhead of feature engineering. The hybrid nature of the model enables it to effectively handle mixed-type features, including text, binary, and numerical data. We design the network using long-short-term memory (LSTM) units. DNN model layers were trained, and the weights of the pre-trained model layers were frozen to apply the transfer learning, resulting in reduced training time and improved bot profile detection accuracy. The performance of the proposed TL-PBot is evaluated using publicly available datasets. The proposed approach is trained and tested on the same datasets and further evaluated on the validation datasets that were not used in the training phase, which is also a novelty in our approach. Comparative analysis with state-of-the-art approaches demonstrates that the TL-PBot approach achieves a higher accuracy of 98.07%, while excelling in precision of 99%, recall of 98%, f measure of 98.32%, and AUC of 0.99. Employing the transfer learning strategy resulted in an accelerated detection rate of 5.04 milliseconds, attesting to the effectiveness of this approach in enhancing computational efficiency.

The research investigated the tooth backlash influences the error in seedling picking trajectories of the gear train SPM. First, a sine function and the sum of random errors are taken into account is utilized to fit the tooth backlash of the firstly and secondary transmissions. Additionally, the analysis established the relationship between the fitting parameters and the tooth backlash of the firstly and secondary transmissions, in order to determine the appropriate fitting parameters. Next, the relationship between the tooth backlash of the firstly and secondary transmission in the seedling picking mechanism (SPM) and the x, y coordinates, as well as the velocity and acceleration of the seedling needle tip (SNT), is examined. This analysis is based on the error and movement variance of the coordinate and kinematic parameters of SNT. The results indicate that the tooth backlash of the firstly transmission has a more significant influence on the error of the seedling picking trajectory compared to the tooth backlash of the secondary transmission. When the tooth backlash of the noncircular gear in the firstly transmission reaches its maximum value of 0.24 mm, the x and y coordinates of the SNT can reach maximum values of 1 and 3.5 mm. The test of the jumping of the needle tip and idling trajectory description indicated that noncircular gears with larger tooth backlash exhibit higher positional jumping at the tip of the seedling needle.

Carbon reduction is an important issue of global concern today, and with the construction industry accounting for a significant portion of global carbon emissions, carbon reduction research for the civil engineering industry is becoming increasingly important. The current research on carbon emission of buildings mainly focus on energy consumption, choice of building materials, and energy-saving technologies. While different construction programs can affect the construction sequence and have a significant impact on carbon emissions, especially for ultra-high-rise steel structures. In this paper, carbon emission is introduced as the optimization objective, and a nodal optimization procedure based on carbon emission is given to explore the optimization scheme of ultra-high-rise steel structure construction based on carbon emission. Calculations using the carbon emission factor method were carried out to analyze the differences in carbon emissions between different construction schemes and to explore the impact of the method of carbon emission optimization. Results show that the combined lifting scheme can save 463.4 kg carbon emissions and reduce the number of lifts by 780 times.

This review aims to present a critical overview of indium tin oxide (ITO) thin film preparation methods, structure–property relationship, and its humidity sensing. A range of passive and active humidity sensors with thin films (based on metal oxides) detects humidity. ITO thin film has advantageous properties, such as low resistivity and high stability, making it highly suitable for humidity sensing applications. ITO thin film has shown the efficient level of humidity sensing, and a compatible size of humidity sensor can monitor the interface conditions humidity. So far, the application of ITO thin film for humidity measurement has yet to be explored at commercial scale, specifically in the detection of lower environmental humidity range (below 5% relative humidity (RH)). The research reveals a gap in improving the ITO thin film properties with an optimal range of preparation conditions. The research opportunities in the preparation, properties, characteristics, and efficient humidity sensitivity of ITO thin film are reviewed in this work.

Energy consumption and operational cost are two decision-making factors which evaluate the feasibility of any energy system. Whether a thermal unit is efficiently working or not depends on the state properties of the thermodynamic system. Therefore, operational research on a geothermal site was performed. Most research pivots around the basic energy conservation equation to determine the parameters. However, finding the parameters does not serve the purpose of an investor. Investment of capital in any project depends on the return and feasibility of the task performed under the project. In the same direction, this article focuses on the optimisation of the performance of a shallow geothermal site in terms of energy and plant economics using the concept of a second-order cone program (SOCP). The site was used to operate the hybrid heating, ventilation, and air conditioning unit (HVAC) installed in an academic building. The second-order cone programming was considered to minimize the energy requirement and cost of energy generation during the winter season. It is to be noted that the solver-based approach was considered to examine the unit. The optimized energy consumption of GSHP was 24.29 kW⋅h. The levelized cost of energy (LCOE/kW⋅h) derived from SOCP would vary from $ 0.38 to $ 0.58 for the shallow geothermal plant. The rate of return for air conditioning in the building through the geothermal plant would be 1.74%. The optimized upfront cost per m² was estimated to be $ 1440.87.