Journal of Engineering
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Aiming at the demand for medium- and high-voltage port access capability in energy router, this study proposes a quad-port DC/DC converter topology scheme based on modular multilevel converter (QP-M2DC). Compared with the traditional multiterminal energy routing converter, it has the advantages of high modularity, strong flexibility, and high power density. In addition, for the modular structure on the medium- and high-voltage sides, this study proposes a narrow phase-shift cyclic modulation strategy, which reduces the system need for voltage balance control and simplifies the overall system control. This study comprehensively introduces and analyses the QP-M2DC topology, working principle, high-frequency link equivalent, and power characteristics, then establishes an equivalent model of system control, and proposes a control scheme for a multiterminal energy routing converter. Finally, a simulation model of the system is established through PLECS, and the simulation results show that in such a narrow phase-shift modulation strategy, the proposed topology can have stable operation in a variety of patterns, reduce the capacitance, and achieve better voltage balance at the same time. The experimental results show the converter efficiency of up to 97.8%. It further shows the superiority of the proposed topology structure and the correctness and effectiveness of the proposed control schemes.

This study shows the torsional conduct of aggregate streaming beams of reinforced concrete recycling. Pure torsion was perceived for 15 reinforced concrete beams containing recycled concrete aggregates. The beams were grouped into five lengths and cross-sectional groups. The study’s principal parameters were the various percentages of longitudinal steel reinforcement and the proportions of recycled aggregates. The beams were purely twisted until failure and investigated for torsional and crack behaviour. The findings show that the beams with maximum steel enhancement and standard aggregate exhibited maximum cracking power and ultimate torsional strength. Recycled aggregates increased the presence of splitting and the ultimate strength, and the effects of steel strengthening in recycled beams were apparent. In a second analysis, the whole torsional reaction of the beams was analytically predicted. A soft truss model was used and matched with test results for standard beams. A strong compromise was generally reached.

This paper aims at the extraction and application of eco- and user-friendly natural gum obtained from Commiphora Africana tree. The result obtained is also compared with fabric treated with a commercial softener of the same concentration. The gum was extracted by puncturing the stem of the plant and the extracted gum was applied directly to 100% cotton fabric through a padding process with different concentrations of extracted gum (i.e., 20 gram per litre (g/l), 25 g/l, and 30 g/l). Another similar fabric sample was treated with a silicon softener of the same concentration. The fabric samples treated with both natural gum and silicon softener were tested for their stiffness, crease recovery, and drapability. The results show that the change in fabric softness depends on the concentration of softener used in both cases. As the concentration of the softener increased, there was a decrease in bending length and drape coefficient for both fabric samples. The drape coefficient of fabric sample treated with natural gum has a comparable result with fabric treated with silicon/commercial softener. Maximum increases in recovery angle were seen in fabric treated with natural gum at a concentration of 30 g/l.

This work presents the regulation of temperature in an indirect multitrays solar dryer with oriented flux under the irradiance fluctuation. The temperature regulator using a negative temperature coefficient (NTC) as a sensor and fans is designed, and a similar device is also used to measure humidity through a sensor. Inlet and outlet dryer temperature and temperature on the three trays have been recorded with the regulation system according to different airflow modes. Irradiance and humidity have also been recorded. The model of outlet temperature with energy storage was given by using heat transfer equations. The results have shown that in the linking airflow mode, the average temperature on the three trays is 51.3 ± 1.5a°C, 52.18 ± 1.4a°C, and 51.9 ± 1.2a°C, respectively, with 52°C as setpoint temperature and NTC fixed on tray number 2. With temperature sensor in the same tray and 51°C as setpoint temperature, the average temperatures on the three trays are 51.86 ± 1.54°C, 51.60 ± 1.16°C, and 50.42 ± 1.13°C, respectively, in mixed mode, whereas in crossing airflow mode, the temperature gradient does not allow regulation on all trays. The regulation is possible when the temperature in the dryer chamber exceeds the set point temperature by more than 5%. The proportional type corrector is suitable for the temperature controller in indirect solar dryers. When the energy source is unstable, humidity which is a variable parameter is used to mark the end of drying instead of time.

Yarn quality influences both fabric production processes efficiency and export market. One method used to gauge competitiveness of an industry is to study its product quality. The aim of this research work is to evaluate the quality of Ethiopian textile spinning mills’ 100% cotton carded ring spun yarns in terms of its evenness (coefficient of mass variation, CVm), imperfections (thick and thin places, neps), and tensile properties with USTER Statistics 2018. Five spinning mills (B3, A0, A2, A4, and K3) of 15N, 20Ne, 25Ne, 30Ne, 35Ne, and 40Ne nominal yarn counts have been selected for the study. The yarn evenness and imperfections were measured using USTER tester 5 and tensile using a STATIMAT tester. The USTER statistical results showed 20.3Ne (mill B3), 32Ne (mill A4), and 36.2Ne (mill A2) had better overall quality, respectively. It was observed that most selected spinning mills had low evenness, imperfections, yarn strength, and good yarn elongation. Tensile properties of A2 (32.85Ne and 36.2Ne) had fallen under 5% USTER statistics percentile which indicates excellent yarn strength. Generally, from studied mills, it was seen that 61.5% of cotton yarn CVm and thin places falls at above 95% and 15% of yarn tenacity falls at ≤5% of Uster statistical percentile.

The world is attesting a tremendous change today, which is remarkably coined as industry 4.0. With several technologies shaping industry 4.0 epoch, notably, its cybersecurity entails the security of communication and network operations activities. The most common form of communication in organisations and business today is electronic mails (email). One of the major threats to email communication is the lack of confidentiality for emails accessed via Android mobile devices due to the weaknesses of the Android operating system (OS) platform. In this study, an algorithm was designed and implemented on an Android application that allows an email sender to compose an email and set the time the email stays in the receiver inbox before it automatically wipes off. Primary data were collected from email users using tightly structured questionnaires and respondents comprised of those with email technical background and typical email users, while secondary data from scholarly journals and articles informed the study design. The designed algorithm was tested and evaluated through expert opinion. The result of the study indicates that the autowipe algorithm addresses the confidentiality issues and threats on Android email clients.

The current work conducts a comparative study of the waterbed multistage solar still with stacked stages (MSS-SS) and the vapour-based MSS-SS. Various experimental test results obtained from the vapour-based MSS-SS are briefly discussed in comparison with the waterbed MSS-SS reported in the literature. Based on the experimental observations and tests, the stage tray requires no maintenance and upper stages can operate even when the lower stages are nonoperational. About 0.8–41.3% distillate yield dropped from the upper stages when lower stages were exposed to the atmosphere. The upper stages increased their productivity by 7.1–15.4% when the lower stages were shut off completely. The waterbed-based MSS-SS preserves and reuses thermal energy much better even during off sunshine hours than the vapour-based system. The vapour-based MSS-SS is only productive during sunshine hours, and about 97-98% of the distillate is produced during daytime. Furthermore, the vapour based was able to produce 6.3 kg/day on average on the selected days.

It is rather difficult for engineers to apply many of the fatigue damage models for requiring a knee point, material-dependent coefficient, or extensive testing, and some of them are only validated by a fatigue test of two-stage loading rather than higher-stage loading. In this paper, we propose a new model of fatigue cumulative damage in variable amplitude loading, which just requires the information of the S-N curve determined from the fatigue experiment. Specifically, the proposed model defines a stress equivalent transformation way to translate the damage of one stress to another stress through simple calculation. Experimental data of fatigue including two-, three-, and four-block loading verify the superiority of the proposed model by comparing it with the Miner model and Manson model. The results show that the proposed model can be generalized to any type of loading and presents a better prediction. Therefore, the advantage of the proposed model can be easily used by an engineer.

Numerical and computational analyses surrounding the behavior of the bearing capacity of soils near or adjacent to slopes have been of great importance in earthwork constructions around the globe due to its unique nature. This phenomenon is encountered on pavement vertical curves, drainages, and vertical infrastructure foundations. In this work, multiple data were collected on the soil and footing interface parameters, which included width of footing, depth of foundation, distance of slope from the footing edge, soil bulk density, slope and frictional angles, and bearing capacity factors of cohesion and overburden pressure determined for the case of a foundation on or adjacent to a slope. The genetic programming (GP), evolutionary polynomial regression (EPR), and artificial neural network (ANN) intelligent techniques were employed to predict the ultimate bearing capacity of footing on or adjacent to a slope. The performance of the models was evaluated as well as compared their accuracy and robustness with the findings of Prandtl. The results were observed to show the superiority of GP, EPR, and ANN techniques over the computational works of Prandtl. In addition, the ANN outclassed the other artificial intelligence methods in the exercise.