Asad Ullah

Loading web-font Gyre-Pagella/Fraktur/Regular Department of Mathematics, Quaid-i-Azam University, Islamabad 45320, Pakistan

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Civil Engineering Department, University of Engineering and Technology, Lahore 54890, Pakistan

Confined masonry (CM) construction is being increasingly adopted for its cost-effectiveness and simplicity, particularly in seismic zones. Despite its known benefits, limited research exists on how the stiffness of confining elements influences the in-plane behavior of CM. This study conducted a comprehensive parametric analysis using experimentally validated numerical models of single-wythe, squat CM wall panels under quasi-static reverse cyclic loading. Various cross-sections and reinforcement ratios were examined to assess the impact of the confining element stiffness on the deformation response, the cracking mechanism, and the hysteretic behavior. The key findings included the observation of symmetrical hysteresis in experimental CM panels under cyclic loading, with a peak lateral strength of 114.3 kN and 108.5 kN in push-and-pull load cycles against 1.7% and 1.3% drift indexes, respectively. A finite element (FE) model was developed based on a simplified micro-modeling approach, demonstrating a maximum discrepancy of 2.6% in the peak lateral load strength and 5.4% in the initial stiffness compared to the experimental results. The parametric study revealed significant improvements in the initial stiffness and seismic strength with increased depth and reinforcement in the confining elements. For instance, a 35% increase in the lateral strength was observed when the depth of the confining columns was augmented from 150 mm to 300 mm. Similarly, increasing the steel reinforcement percentage from 0.17% to 0.78% resulted in a 16.5% enhancement in the seismic strength. These findings highlight the critical role of the stiffness of confining elements in enhancing the seismic performance of CM walls. This study provides valuable design insights for optimizing CM construction in seismic-prone areas, particularly regarding the effects of confining element dimensions and reinforcement ratios on the structural resilience.

IntroductionSquamous cell carcinoma of the thyroid (SCCT) is a rare, aggressive thyroid cancer distinguished by the emergence of squamous cells due to chronic inflammation or metaplasia. It poses diagnostic and therapeutic challenges, often identified at an advanced stage with a poor prognosis. The rarity of SCCT underscores the necessity for advanced research on effective treatments and diagnostic strategies. The current data utilized the Surveillance, Epidemiology, and End Results (SEER) database to determine the characteristics and outcomes of patients with primary SCCT.MethodsDe-identified data from patients with primary SCCT from 2000 to 2020 were collected using the SEER database. Demographic data, including age, sex, race, income, and housing, and clinical data including tumor size, tumor stage, nodal status, metastases, treatment modality, survival, and the patient’s status, were extracted. Exclusion criteria were patients with unknown outcomes and missing death certificates. A detailed comparison of the two patient cohorts and univariate and multivariate Cox proportional hazard regression survival analyses were conducted.ResultsAmong the 159 primary SCCT patients, the median age was 71 ± 21 years, with 83 females (52.2%) and 76 males (47.8%). The median overall follow-up was 6.0 years (4.41-7.59). The majority were White (108, 67.9%), followed by Hispanic (19, 11.9%). The five-year overall survival (OS) of the study group was 17.6% (95% CI = 14.5-20.7). The five-year disease-specific survival (DSS) was 37.6% (95% CI = 32.7-42.5). There was no significant difference based on surgery, chemotherapy, or radiation (p = 0.134). Age, tumor stage, nodal status, and distant metastases were negative prognostic factors. Sex, race, income, and housing were not predictive of survival.ConclusionThe current study on SCCT highlights a low five-year OS rate of 17.6% and a DSS rate of 37.6%, with no significant difference in survival based on surgery, chemotherapy, or radiation. The negative prognostic factors included age, tumor stage, nodal status, and distant metastases, whereas sex, race, income, and housing did not significantly predict survival outcomes. These findings underscore the critical need for early detection and the development of more effective treatment strategies to manage SCCT.

Yingzhu Zi Anjun Huang Heping Zhao Xue Bai Zan Xu Asad Ullah

A novel ground slot-based massive multiple-input multiple-output (MIMO) system with 14 elements for dual-band application of next-generation smartphones is developed. Every single antenna in the array is placed on the borders of a smartphone's PCB, operating within the 3.55 GHz to 3.7 GHz (n48) and 5.855 GHz to 5.925 GHz (n47) frequency bands. This study also further assesses the performance of this system with analytical results, in which the self-s-parameters are less than −6 dB for each antenna, whereas isolation between components is less than −10 dB. At the same time, the overall efficiency reaches 65.55% and higher in the whole band. The evaluation of MIMO performance parameters such as envelope correlation coefficient (ECC), and DG of the MIMO system is well performed. A proposed MIMO antenna system is deployed and analyzed, which is a massive MIMO antenna, and the simulation results are compared to the measurement. The results validate the fact that the design of this particular MIMO system suits it to be incorporated in the n47 and n48 frequency bands, and therefore the presented MIMO system is suitable to be an option for integration into the upcoming smartphone architecture.

In electromechanical systems, backlash in gear trains can lead to a degradation in control performance. We propose a drive–anti-drive mechanism to address this issue. It consists of two DC motors that operate in opposite directions. One motor acts as the drive, while the other serves as the anti-drive to compensate for the backlash. This work focuses on switching between the drive and anti-drive motors, controlled by a switched-mode PID controller. Simulation results on an inverted pendulum demonstrate that the proposed scheme effectively compensates for backlash, improving position accuracy and control. This switched controller approach enhances the performance of electromechanical systems, particularly where gear backlash poses challenges to closed-loop performance.

Article Sidebar Published: Dec 31, 2024 DOI: https://doi.org/10.35845/kmuj.2024.23579 Keywords:

The Syrian conflict presents a pivotal opportunity for China to exhibit its readiness to assume a true global leadership role.