Development of vertical diffusion solar stills utilizing folded sheets technology

Fresh water shortage is now a global problem the world is facing, and solar stills address a sustainable solution towards such crisis. This study entails the importance of desalination, specifically solar distillation. Diffusion stills have been effective in water desalination. This work presents a model of the distillation process using vertical single-effect diffusion stills. In the provided models, two geometry patterns have been utilized: the flat sheets and the folded sheets. This study aims to evaluate the applicability of utilizing folded sheets on the performance of the still using wick and without wick. A semi-analytical model utilizing the flat sheet and the folded sheet have been developed to analyze the diffusion process. Furthermore, a software computer code using Engineering Equation Solver (EES) issued to solve the equations of the developed semi-analytical model. An experimental test rig has been constructed, and used for the validation of the semi-analytical model to find its best range of validity. Also, it is validated against former literature results. A good agreement is reached with feed rates of flow up to 0.0211 kg/m2-s. Moreover, a parametric study for the still utilizing flat sheets model is carried out to assess the performance of the still; it is found that the controllable parameters are:(i) hot plate temperature; (ii) cold plate temperature;(iii) diffusion gap thickness;(iv)feed water temperature; and (v) feed rate of flow; have an impact on the still’s productivity. The most dominant parameters that influence the productivity of the still are the hot plate temperature that ranges from (55- 90 °C), the diffusion gap thickness in range of (5-10 mm), the feed water temperature (20-50 °C), and the feed flow rate in range of (0.00694-0.0211 kg/m2-s). The experimental work utilizing folded-chevron pattern sheets, both with wick and wickless, have been carried out and have been compared to the flat sheets to assess still’s productivity. A comparative analysis has been conducted to evaluate the productivity; it is found that the folded sheet with wick has a higher productivity among other sheets. It indicates the superiority of the wicked folded over the wickless folded and the flat sheet. The folded pattern showed a higher performance by an average increase in the condensate to feed ratio by 27 % through the operating hot plate temperature that ranges from 60 to 90°C

Survey on Applications of Machine Learning in Low-Cost Non-Coherent Optical Systems: Potentials, Challenges, and Perspective

Direct Detection (DD) optical performance monitoring (OPM), Modulation Format Identification (MFI), and Baud Rate Identification (BRI) are envisioned as crucial components of future-generation optical networks. They bring to optical nodes and receivers a form of adaptability and intelligent control that are not available in legacy networks. Both are critical to managing the increasing data demands and data diversity in modern and future communication networks (e.g., 5G and 6G), for which optical networks are the backbone. Machine learning (ML) has been playing a growing role in enabling the sought-after adaptability and intelligent control, and thus, many OPM, MFI, and BRI solutions are being developed with ML algorithms at their core. This paper presents a comprehensive survey of the available ML-based solutions for OPM, MFI, and BFI in non-coherent optical networks. The survey is conducted from a machine learning perspective with an eye on the following aspects: (i) what machine learning paradigms have been followed; (ii) what learning algorithms are used to develop DD solutions; and (iii) what types of DD monitoring tasks have been commonly defined and addressed. The paper surveys the most widely used features and ML-based solutions that have been considered in DD optical communication systems. This results in a few observations, insights, and lessons. It highlights some issues regarding the ML development procedure, the dataset construction and training process, and the solution benchmarking dataset. Based on those observations, the paper shares a few insights and lessons that could help guide future research

PAPR Reduction in UFMC for 5G Cellular Systems

Universal filtered multi-carrier (UFMC) is a potential multi-carrier system for future cellular networks. UFMC provides low latency, frequency offset robustness, and reduced out-of-band (OOB) emission that results in better spectral efficiency. However, UFMC suffers from the problem of high peak-to-average power ratio (PAPR), which might impact the function of high power amplifiers causing a nonlinear distortion. We propose a comparative probabilistic PAPR reduction technique, called the decomposed selective mapping approach, to alleviate PAPR in UFMC systems. The concept of this proposal depends on decomposing the complex symbol into real and imaginary parts, and then converting each part to a number of different phase vectors prior to the inverse fast Fourier transform (IFFT) operation. The IFFT copy, which introduces the lowest PAPR, is considered for transmission. Results obtained using theoretical analysis and simulations show that the proposed approach can significantly enhance the performance of the UFMC system in terms of PAPR reduction. Besides, it maintains the OOB emission with candidate bit error rate and error vector magnitude performances

Lingual mucosal graft two-stage Bracka technique for redo hypospadias repair

Objectives: To report our initial experience in redo hypospadias repair with a lingual mucosal graft (LMG) using a two-stage Bracka technique. Patients and methods: This study was prospectively conducted and included 26 patients with hypospadias with failed previous repairs. All the patients had a LMG using a two-stage Bracka technique. In the first stage, the harvested LMG, from the ventro-lateral surface of the tongue, was implanted in a well-prepared vascularised bed in the ventral aspect of the penis. After 6 months, tubularisation of the well-taken graft was completed. Tunica vaginalis or a dartos flap was used as second-layer coverage of the neourethra. Success was defined as acceptable aesthetic and functional outcomes without any additional surgical interventions. Results: The mean (SD) patient age was 5.15 (1.6) years. The mean (SD) LMG length was 3.82 (0.9) cm and the width was 1.5 (0.5) cm. The mean (SD) number of previous repairs was 2.76 (1.1). The mean (SD) follow-up was 12 (2) months. Donor-site complications included: pain in all patients, with a pain score of >3 on the visual analogue pain scale (0–10) in 10 (38%); and speech problems in 19 (73%). First-stage complications were graft loss (n = 2) and contracture (n = 1). The second stage was completed in 23 patients resulting in the following significant complications: meatal stenosis plus fistula (n = 2), breakdown (n = 1). Successful hypospadias repair was achieved in 77% (20/26) of the patients. Conclusion: Lingual mucosa is a reliable and versatile graft material in the armamentarium of two-stage Bracka hypospadias repair with the merits of easy harvesting and minor donor-site complications