High-Torque-Density Low-Cost Magnetic Gear Utilizing Hybrid Magnets and Advanced Materials

Two major challenges of existing high-performance magnetic gears are: (i) High content of rare-earth permanent magnets which results in high cost as well as price fluctuation; (ii) Conflict between mechanical and electromagnetic performances, especially in the design of highspeed rotor. A magnetic gear using a blend of magnet types, i.e NdFeB, or Dy-free NdFeB and ferrites, is proposed in this paper. The goal is to bring down the cost while retaining comparable torque-transducing performance to a baseline magnetic gear only using rare-earth NdFeB magnets. A variety of topologies based on different combinations of magnet types and geometric shapes have been studied and compared. In addition, the potential impact of using an advanced dual-phase material is evaluated. The goal is to eliminate the well-known tradeoff between rotor mechanical integrity and PM flux leakage

Optimal Conditions for Electrodeposition of Copper (II) in Presence of Alizarin Red’s by Physicochemical Methods

The comprehensive physical properties of the aqueous  solutions of (alizarin red S - copper(II) chloride) were studied in this research with fixing the conditions (pH – concentration – temperature), then the optimal conditions for the formation of the complex Copper(II) – Alizarin Red S (ARS – Cu II) were appointed by several ways: (the pH measurement method - electrical conductivity measurement method – UV/Vis spectral method), and then the stoichiometry of the reaction of the complex formation was determined by three reference methods. It found that the complex formed when each concentrations greater than a certain limit (10-5 M). In addition, the complex could formed at higher concentrations by adjusting the (pH) at a suitable value (4.2 → 5.8). Finally, the complex remains stable with the time keeping at suitable conditions (a way from the sun light and a way from a high temperature). Also, the electrodeposition of copper(II) was studied to determine the appropriate operating conditions and the thicknesses of the coating layer. It was obtained a good properties (brightness - surface covering: distribution of atoms - thickness ....... etc.). of deposit without using of any other additives by applying the conditions (pH = 5, i = 2 mA/cm2, t = 5 min, C = 0.1 M  d = 1.756×10-5 cm). Keywords: Alizarin red S - (ARS – Cu II) complex - electrodeposition of Cu (II)

Statistical PT-symmetric lasing in an optical fiber network

PT-symmetry in optics is a condition whereby the real and imaginary parts of the refractive index across a photonic structure are deliberately balanced. This balance can lead to a host of novel optical phenomena, such as unidirectional invisibility, loss-induced lasing, single-mode lasing from multimode resonators, and non-reciprocal effects in conjunction with nonlinearities. Because PT-symmetry has been thought of as fragile, experimental realizations to date have been usually restricted to on-chip micro-devices. Here, we demonstrate that certain features of PT-symmetry are sufficiently robust to survive the statistical fluctuations associated with a macroscopic optical cavity. We construct optical-fiber-based coupled-cavities in excess of a kilometer in length (the free spectral range is less than 0.8 fm) with balanced gain and loss in two sub-cavities and examine the lasing dynamics. In such a macroscopic system, fluctuations can lead to a cavity-detuning exceeding the free spectral range. Nevertheless, by varying the gain-loss contrast, we observe that both the lasing threshold and the growth of the laser power follow the predicted behavior of a stable PT-symmetric structure. Furthermore, a statistical symmetry-breaking point is observed upon varying the cavity loss. These findings indicate that PT-symmetry is a more robust optical phenomenon than previously expected, and points to potential applications in optical fiber networks and fiber lasers.Comment: Submitted to Nature Communications, Pages 1-19: Main manuscript; Pages 20-38: Supplementary material

Performance indexes of BSS for real-world applications

Publication in the conference proceedings of EUSIPCO, Florence, Italy, 200

Assessment of Chemical Characteristics of the Desalinated Water Used in Household Facilities in Gaza Strip

Access to safe water represents one of the most important basic human needs of the people of Palestine and is vital to a growing economy and a healthy population. Groundwater is the major source of water to the Palestinians. Nowadays, the water crisis in the Strip is multiplying. The objective of this research is to make an assessment of the desalination plants for the chemical quality for both the inlet (groundwater) and the outlet water (product water) in the desalination plants. The adopted methodology depends on many approaches that were used in an integrated manner to achieve the objectives of this research. Samples from both the inlet and outlet water from 88 desalination plants have been collected by the researcher. The main chemical parameters have been analyzed in the inlet and outlet water of the desalination plants. The study proved that the current private desalination monitoring program by the concerned authorities should be developed, enhanced and intensified. The study also revealed that the current private desalination plants were established randomly and for commercial purposes without any previous planning. The results have revealed that 80% of the inlet water of the plants does not comply with the WHO guidelines, while 100% of the plants’ outlet water has chemical parameter concentrations accepted by the WHO guidelines. Keywords: Groundwater, contamination, brackish water, desalination plants, Gaza Strip, chemical parameters

Field Cracking Performance of Rigid Pavements

This paper discusses cracking in airport pavements as studied in Construction Cycle 6 of testing carried out at the National Airport Pavement Testing Facility by the Federal Aviation Administration. Pavements of three different flexural strengths as well as two different subgrades, a soft bituminous layer and a more rigid layer known as econocrete, were tested. In addition to this, cracking near two types of isolated transition joints, a reinforced edge joint and a thickened edge joint, was considered. The pavement sections were tested using a moving load simulating that of an aircraft. It has been determined that the degree of cracking was reduced as the flexural strength of the pavement was increased and that fewer cracks formed over the econocrete base than over the bituminous base. In addition, the thickened edge transition joint was more effective in preventing cracking at the edges compared to the reinforced edge joint

Transparent Perfect Mirror

A mirror that reflects light fully and yet is transparent appears paradoxical. Current so-called transparent or "one-way" mirrors are not perfectly reflective and thus can be distinguished from a standard mirror. Constructing a transparent "perfect" mirror has profound implications for security, privacy, and camouflage. However, such a hypothetical device cannot be implemented in a passive structure. We demonstrate here a transparent perfect mirror in a non-Hermitian configuration: an active optical cavity where a certain prelasing gain extinguishes Poynting's vector at the device entrance. At this threshold, all vestiges of the cavity's structural resonances are eliminated and the device presents spectrally flat unity-reflectivity, thus, becoming indistinguishable from a perfect mirror when probed optically across the gain bandwidth. Nevertheless, the device is rendered transparent by virtue of persisting amplified transmission resonances. We confirm these predictions in two photonic realizations: a compact integrated active waveguide and a macroscopic all-optical-fiber system.Comment: The paper is highlighted in Nature Photonics: http://www.nature.com/nphoton/journal/v11/n6/full/nphoton.2017.90.html The supplementary data is available in: http://pubs.acs.org/doi/suppl/10.1021/acsphotonics.7b0005

Bipolar versus fixed-head hip arthroplasty for femoral neck fractures in elderly patients

Between 2002 and 2007, fifty elderly patients with displaced femoral neck fractures were treated with hip replacement at Emergency Hospital, Mansoura University. Patients were randomly selected, 25 patients had either cemented or cementless bipolar prosthesis, and another 25 patients had either cemented or cementless fixed-head prosthesis. There were 34 women and 16 men with an average age of 63.5 years (range between 55 and 72 years). All patients were followed up both clinically and radiologically for an average 4.4 years (range between 2 and 6 years). At the final follow-up, the average Harris hip score among the bipolar group was 92 points (range between 72 and 97 points), while the fixed-head group was 84 points (range between 65 and 95 points). Radiologically, joint space narrowing more than 2 mm was found in only 8% (2 patients) among the bipolar group, and in 28% (7 patients) of the fixed-head group. Through the follow-up period, total hip replacement was needed in two cases of the bipolar group and seven cases of the fixed-head group. Bipolar hemiarthroplasty offered a better range of movement with less pain and more stability than the fixed-head hemiarthroplasty in elderly patients with displaced femoral neck fractures

Humanizing Pedagogy: Minimizing Negative Teacher Talking Time on the Teaching of English Language as a Foreign Language

The study aims at studying minimizing negative teacher talking time as a tool of humanizing teaching English language as foreign language in Saudi Arabia context. The study accentuates the variety conceptual perspective of teaching talking time and its main causes. The study is based on quasi-experiment method and 50 students were divided into two groups; one group taught through minimizing teacher talking time and maximizing student teacher talking time interactively, whereas, the other group is taught deductively. The study found out that minimizing teacher talking time and maximizing student’s time talking time enhance humanization sense of learning English language among Saudi learners and it promotes interactive motivational sense among the learners. The experimental group students’ outcomes revealed positive gains through maximizing student talking time and positive interactive English practice in English classroom. This study is one of the forerunner studies which play a salient role in shed lighting on the importance of humanizing teaching English in Saudi Arabia context through minimizing teacher talking time. The study recommends that teaching English language should be based on learner centeredness relying on minimizing negative teacher talking time and maximizing student talking time through using pedagogic techniques and strategies. Keywords: Teacher talking time, negative teacher talking time, positive  teacher talking time efficiency, humanization . DOI: 10.7176/JLLL/77-07 Publication date:March 31st 2021