Journal of Engineering Research最新文献

This study evaluated the durability of concrete incorporating different silica fume (SF) content and also computed the service life of this concrete in marine environments. The specimens were prepared with three different SF content (i.e. 8%, 10%, and 12% by mass of cement replaced with SF). Three water/binder ratios (0.25, 0.30, and 0.35) were used for preparing concrete specimens. The mechanical properties were assessed via compression and splitting tensile tests. The rapid chloride penetration and chloride migration experiments were employed to evaluate the durability of concrete. The results showed that the mixture with 10% SF replacement showed the best performance. The inclusion of SF not only reduced the total porosity but also refined the volume fraction of harmless and less harmful pores (< 200 nm). Consequently, the chloride ion penetration resistance of concrete was improved, which in turn reduced the potential corrosion rate of reinforcement. From the results of service life prediction using Life-365 software, it is indicated that the utilization of SF for cement replacement effectively improved the corrosion resistance of steel bars in marine reinforced concrete. The service life against salt damage can be remarkably extended by substituting cement with an appropriate SF level.

The increased market activity and visibility have resulted in a growing demand for additional computer resources to meet the needs of cloud clients. Delivering promised quality of service (QoS) while fulfilling diverse resource demands dynamically might be difficult for a single Cloud Service Provider (CSP). Federated cloud computing, also known as distributed cloud computing, is an established paradigm in which CSPs collaborate to aggregate unused resources, resulting in financial and QoS benefits. Notably, this strategy improves availability and reliability while overcoming individual CSP difficulties in preserving QoS amid fluctuations in resource demand. The federated cloud successfully leverages computing resources even during low-demand periods, demanding a comprehensive resource management strategy for Infrastructure as a Service (IaaS) inside participating CSPs. Such a strategy is crucial for preserving QoS, ensuring availability and dependability, and optimizing underutilized computing resources. This research presents the novel IaaS cloud design, revealing a unique methodology that reimagines traditional cloud systems. The proposed IaaS cloud framework investigates virtual machine migration and resource consolidation, building a strong foundation founded on IaaS principles and emphasizing the crucial role of virtualization. The technique introduces ground-breaking concepts such as Cloud User (CU) and Reputation Management, which are strengthened by specific algorithms that improve cloud service security and trust. Furthermore, the combination of Trust Manager (TM) and Broker Manager (BM) components strengthens SLA control and trust evaluation, aligning smoothly with IaaS standards to improve service quality and reliability. User Profiling, which is classified into private, social, and corporate profiles, provides a separate lens for successful cloud user management inside the IaaS landscape, allowing for customised service delivery. SMI and cutting-edge ranking algorithms, such as the Deep Q-based Algorithm, optimize cloud service provider selection and ranking—an important aspect of IaaS. The use of the Banker's algorithm and a comprehensive Service Level Agreement (SLA) Management plan provides efficient resource allocation, mirroring recognized IaaS standards. This research study not only throws light on these trailblazing techniques, but it also establishes a new standard for IaaS cloud design and resource management.

In order to improve the quality of physiological signals, a combined study of blind source separation and wavelet thresholding methods was conducted, resulting in the proposal of a multispectral adaptive wavelet denoising (MAWD) method. This method was employed in conjunction with an improved unsupervised source counting algorithm (USCA). To evaluate the effectiveness of the proposed approach, three methods were used to calculate signal-to-noise ratio (SNR) and root mean square error (RMSE): soft thresholding, hard thresholding, and adaptive thresholding. The results demonstrated that the proposed method exhibited strong applicability under soft thresholding. Specifically, compared to hard thresholding, the enhanced signal using soft thresholding showed an approximately 44.2% increase in SNR and a 28.8% decrease in RMSE, along with a 1.4% reduction in processing time. Moreover, when compared to adaptive thresholding, soft thresholding exhibited approximately 706% improvement in SNR, a 16.7% decrease in RMSE, and a 3.0% reduction in processing time. Multiple experiments were conducted to determine the optimal peak detection threshold range for USCA, which was found to be within the interval [0.001, 0.0001]. This range facilitated the separation of more sources, thereby enhancing the separation effectiveness and accuracy. To substantiate the effectiveness of the USCA method, tests were conducted on publicly available datasets of EMG, ECG, and EEG signals, all of which consistently demonstrated the advantages of this approach.

Data Availability

The authors do not have permission to share data.

The radiation (beta particles (β), protons (¹H), α-particles (He²⁺), carbon ions (C⁶⁺), fast neutrons (FN), and thermal neutrons (TN)) absorption parameters of 75TeO₂–10MoO₃–10BaO–(5-x)Sm2O3–xBi₂O₃ glass system were evaluated and presented along with their optical parameters in this study. The parameters were analyzed with the objective of evaluating the role of Sm and Bi atoms in altering the optical and radiation characteristics of the glass system. Starting with high-purity chemicals, namely BaCO₃, Bi₂O₃, MoO3, TeO₂, and Sm₂O₃, and following the melt-and-quench procedure, 75TeO₂–10MoO₃–10BaO–(5-x)Sm₂O₃–xBi₂O₃ glasses were prepared as TeMoBa-Sm/Bi1, TeMoBa-Sm/Bi2, TeMoBa-Sm/Bi3, TeMoBa-Sm/Bi4, and TeMoBa-Sm/Bi5 for Bi₂O₃ molar concentration of 0, 2, 4, 4.5, and 5 mol %, respectively. The optical parameters were computed theoretically from measured absorption spectra. The stopping powers and ranges of β-particles, protons, and α-particles were estimated using the ESTAR, PSTAR, and ASTAR software, respectively, while the SRIM code was used to compute for heavy carbon ions. In addition, the cross-sections of fast (FN) and thermal (TN) neutrons were computed using the standard expressions. There was a positive correlation between Bi₂O₃ content and the molar volume of the glasses. The refractive indices vary slightly between 2.53 and 2.56. The molar refractivity ($R_m$) values for TeMoBa-Sm/Bi1, TeMoBa-Sm/Bi2, TeMoBa-Sm/Bi3, TeMoBa-Sm/Bi4, and TeMoBa-Sm/Bi5 are 19.769 cm³/mol, 19.7³0 cm³/mol, 19.689 cm³/mol, 19.656 cm³/mol, and 19.754 cm³/mol, respectively. The values of $S_p$ for proton are highest at 0.09 MeV with values of 284.047, 281.041, 278.135, 277.434 and 276.633 MeV cm²/g for TeMoBa-Sm/Bi1, TeMoBa-Sm/Bi2, TeMoBa-Sm/Bi3, TeMoBa-Sm/Bi4, and TeMoBa-Sm/Bi5, respectively. The Bi₂O₃ content thus improved the CR shielding ability of the glass system slightly. The optimum Bi₂O₃ concentration for FN shielding is 4 mol %. In addition, Bi₂O₃ compromised the TN absorption ability of the TeMoBa-Sm/Bi glass system.

Background

Chaotic oscillations within the power system give rise to instability. While these oscillations may not have an immediate impact on the synchrony of the machine, they stimulate one of the oscillation modes, ultimately leading to voltage collapse and a loss of synchronism.

Objective

This paper introduces a modified Whale Optimization Algorithm (WOA)-based Battery-STATCOM (Static Synchronous Compensator) as a solution to mitigate chaotic oscillations within a Single Machine Infinite Bus (SMIB) system.

Methodology

An adaptable controller is implemented to manage the gate signal within the Battery-STATCOM. The AC-DC currents of this controller are optimally governed by two distinct WOA-tuned Proportional-Integral (PI) controllers. The battery storage unit serves as a robust voltage source, with the intelligent controller maintaining the DC-link voltage at the desired level.

Test Cases

Additional disturbances, such as gradual variations in reference voltage and electromagnetic torque, are introduced to exacerbate chaotic oscillations. This is done to assess the controller's real-world performance under adverse conditions.

Results and Conclusion

Under zero damping conditions, rotor parameters, including rise time, settling time, peak time, and overshoot, initially remain undefined due to uncontrolled oscillations. However, once the Battery-STATCOM is applied, these parameters are defined and achieve values (in seconds) of 0.90, 6.21, 1.71, and 21.10, respectively. After further optimization through the proposed modified WOA optimizer, the parameters reach values of 0.25, 1.01, 0.89, and 1.78, respectively. These results underscore the effectiveness of the proposed metaheuristic controller in suppressing overall chaotic oscillations within the power system.

This study presents the details of the Galerkin finite volume method for triangular unstructured meshes and its application for the fracture analysis of 2D elasticity problems under simultaneous thermal and mechanical loading. The heat diffusion and elasticity equations are discretized using the Galerkin finite volume method (which, due to omitting matrix manipulation calculations, computations are considerably faster than FEM and XFEM Solvers). The maximum tangential stress criterion is presented after briefly describing the interaction integral formulation used to calculate the stress intensity factors in thermo-mechanical problems. The accuracy of the computed results of the present strategy under thermo-mechanical loads is demonstrated using some benchmark test cases. First, a thermal stress analysis of a plate with an inclined central crack under thermal boundary conditions is performed. Second, the development of a crack under mechanical stress boundary conditions is modeled. Third, crack propagation under both thermal and mechanical boundary conditions is simulated. The present modeling strategy's results are compared with those reported in previous numerical works to verify the accuracy. The stress intensity factors and predicted crack trajectories are utilized to assess the accuracy of computed results and investigate the quality of crack simulation by the proposed numerical method.

In mass production, welding flaw detection in existing surface mount technology (SMT) has certain constraints, including its high costs, heavy workloads, and time-consuming processes. However, image classification technology using computer vision demonstrates high detection speeds and considerably reduced detection costs in flaw detection. Nevertheless, the increased integration of chip components on printed circuit boards (PCBs) and reduced component sizes pose challenges for flaw detection technology. Therefore, in this paper, an SMT welding image flaw classification model—that is, the ResNet-34-ECA model—based on an improved ResNet model, is proposed. Initially, the dataset is amplified using data amplification methods, such as stochastic rotation, increased data diversity, and enhanced model robustness. The ResNet34 model is then optimized using the light quantization efficient channel attention (ECA) module, resulting in higher classification accuracy. The experimental data in this study were collected using automated optical inspection (AOI) equipment, following the manual creation and amplification of the dataset. The experimental results showed that the baseline model accuracy increased by 0.22 in the augmented dataset, reaching 97.2%. Moreover, the ResNet-34-ECA model proposed in this paper could realize the classification of SMT welding image defects successfully; the overall classification accuracy of the improved ResNet image classification model was 0.01 higher than that of the baseline model, reaching 98.2%. Consequently, the proposed model proves to be better than other models in defect classification on this dataset, providing an accurate classification of SMT welding image defects.

Cancer therapies are currently limited to surgery, radiation, and chemotherapy. All three methods risk damage to normal tissues or incomplete eradication of the cancer. Nanotechnology offers the means to target chemotherapies directly and selectively to cancerous cells and neoplasms, guide in surgical resection of tumors, and enhance the therapeutic efficacy of radiation-based and other current treatment modalities. All of this can add up to a decreased risk to the patient and an increased probability of survival. In the recent research, the properties of green formulation of silver nanoparticles by Malva sylvestris on human renal cell carcinoma cells were checked. The NPs characterization was run by the techniques of FT-IR, TEM, FE-SEM, and UV-Vis. The MTT assay was used to measure anti-renal cell carcinoma (against RCC-JW (KTCTL-195), RCC-GH, CaKi-2, and HEK293 cell lines) and cytotoxicity (against HUVEC cell line) activity of silver NPs. Interestingly, the nano-drug could resist significantly against those cell lines in a time and concentration-dependent manner, assessed by MTT method. The corresponding IC₅₀ values of the nanoparticles were 118, 135, 66, and 147 µg/ml respectively against the RCC-JW (KTCTL-195), RCC-GH, CaKi-2, and HEK293 renal cell carcinoma cells, respectively. After doing the clinical trial studies, the recent silver nanoparticles may be used for the treatment of renal cell carcinoma in humans.

This paper proposes that the light intensities of adjacent interior spaces should be concurrently evaluated to reduce the risk of glare when evacuees transition between spaces to reach the final exit. The prevention of glare during daytime evacuation has the potential to smoothen the evacuation process from a building. As all legislative, regulatory, and assessment tool recommendations currently used in Malaysia measure illuminance (in lux), this paper similarly evaluates illuminance instead of luminance for ease of initial adoption in the country. Illuminance recommendations in MS1525:2019, LEED, DOSH Guidelines, UBBL, GBI, GreenRE, Melaka Green Seal, and MyCREST were compared to determine the contrast ratio. The illuminance contrast is greatest at the final exit points, such as from parking structures, lobbies, and staircases, which are benchmarked against the Malaysian sky illuminance that can reach 100,000 lux. A contrast ratio as high as 2000:1 may occur if Malaysian offices were designed to only achieve the minimum illuminance requirements. Of the three assessed final exit spaces, naturally-lit fire escape staircases were selected for modelled simulation of illuminance performance using VELUX Daylight Visualiser 2. The findings ascertained that most typical staircase layouts are able to exceed the minimum illuminance requirements at noon, when the sun is potentially the most intense, although the contrast ratio may still reach 1480:1. While the contrast between intermediate spaces are acceptable, those between the final exit transitions and the outdoors are high, suggesting a risk of glare. Further studies are required to determine strategies to facilitate visual adaptation for Malaysians, such as the identification of an ideal acceptable illuminance contrast ratio, temporal adaptation period, or distance-based parameters.

During the construction of earth−rock dams in cold regions, the freezing−thawing of impervious soil causes significant changes in its physical and mechanical properties, which affects the quality and operation safety of the project. To enhance the impervious soil anti−freezing capacity, the hollow polycarbonate panel heating method (HPPHM) was innovatively proposed. Based on the mechanism and in−situ tests, the heating mechanism and effect of HPPHM on impervious soil were investigated. The test results indicated that HPPHM can primarily heat the soil through solar radiation, raising the soil temperature. Furthermore, the air layer inside the panel serves as thermal insulation, effectively preventing the soil internal heat from dissipating. The in−situ test results showed that soil freezing was not observed under HPPHM, and the soil surface temperature was approximately 6 °C higher compared to the control site. The heating influence depth of HPPHM on the impervious soil was approximately 175 cm. Additionally, the soil heat under HPPHM experienced a significant increase of 12537.1 kJ. This study provides a scientific method for improving construction efficiency and quality in cold regions.