Relaxation of writhe and twist of a bi-helical magnetic field

In the past few years suggestions have emerged that the solar magnetic field might have a bi-helical component with oppositely polarized magnetic fields at large and small scales, and that the shedding of such fields may be crucial for the operation of the dynamo. It is shown that, if a bi-helical field is shed into the solar wind, positive and negative contributions of the magnetic helicity spectrum tend to mix and decay. Even in the absence of turbulence, mixing and decay can occur on a time scale faster than the resistive one provided the two signs of magnetic helicity originate from a single tube. In the presence of turbulence, positively and negatively polarized contributions mix rapidly in such a way that the ratio of magnetic helicity to magnetic energy is largest both at the largest scale and in the dissipation range. In absolute units the small scale excess of helical fields is however negligible.Comment: 6 pages, 9 figures, to be published in Astron. Astrophy

Investigating the Role of Critical Success Factors in Achieving the Success of Agile Projects in the Gaza Strip

Achieving project success is a critical element of project management, and identifying the critical success factors (CSFs) that contribute to it is imperative. Agile project management has gained significant attention due to its flexibility, adaptability, and iterative approach, but achieving project success in agile projects remains a challenge. In order to identify the CSFs that have a significant impact on project outcomes, this study examines the role of CSFs in achieving project success in agile projects. A structured online questionnaire was used to collect data from 109 project managers and team members working on agile projects, which was then analyzed using various statistical methods. According to the study\u27s findings, seven factors significantly influence the success of projects: scope and cost management, leadership, agile analytics techniques, customer involvement, teamwork, planning and scheduling, and effective communication, which account for 71.9% of the total variance explained by the CSFs components. The analysis of Pearson correlation coefficients between CSFs and agile project outcomes indicates a positive correlation between each CSF and the four project outcomes (timeliness, cost, quality, and customer satisfaction). The regression analysis includes two significant predictors: scope and cost management, and planning and scheduling, explaining 67.7% of the variation in project outcomes. The findings provide valuable insights for project managers in the Gaza Strip to enhance project success with agile methods by focusing on CSFs

Exploring the Relationship between Green IT Awareness and Adoption: A Case Study of IT Students in the Gaza Strip

Green computing, also known as GIT, has emerged as a crucial field in response to environmental concerns. This study focuses on assessing the level of GIT awareness and adoption among IT students at Al-Aqsa University in Gaza, as well as examining the relationship between GIT awareness and adoption. Data was collected through an online questionnaire completed by 273 participants. The questionnaire covered various aspects of GIT awareness, including understanding, environmental awareness, and e-waste awareness. The collected data was analyzed using statistical techniques such as principal component analysis, mean, and standard deviation. The results indicated that students possessed a satisfactory level of understanding of GIT concepts and the reasons for its adoption. Furthermore, the findings highlighted the significant impact of GIT awareness factors, including GIT understanding, environmental awareness, and e-waste awareness, on GIT adoption. However, it was observed that students did not consistently adhere to GIT guidelines, particularly in terms of frequent internet access and extended computer usage. Interestingly, no significant relationship was found between GIT adoption and students' academic standing. These findings provide valuable insights into the current state of GIT awareness and adoption among IT students and underscore the need for further efforts to promote sustainable computing practices

Influence of calcium-binding salts on heat stability and fouling of whey protein isolate dispersions

peer-reviewedThe effect of the calcium-binding salts (CBS), trisodium citrate (TSC), tripotassium citrate (TPC) and disodium hydrogen phosphate (DSHP) at concentrations of 1–45 mm on the heat stability and fouling of whey protein isolate (WPI) dispersions (3%, w/v, protein) was investigated. The WPI dispersions were assessed for heat stability in an oil bath at 95 °C for 30 min, viscosity changes during simulated high-temperature short-time (HTST) and fouling behaviour using a lab-scale fouling rig. Adding CBS at levels of 5–30 mm for TSC and TPC and 25–35 mm for DSHP improved thermal stability of WPI dispersions by decreasing the ionic calcium (Ca2+) concentration; however, lower or higher concentrations destabilised the systems on heating. Adding CBS improved heat transfer during thermal processing, and resulted in lower viscosity and fouling. This study demonstrates that adding CBS is an effective means of increasing WPI protein stability during HTST thermal processing

Weak Alfvén-wave turbulence revisited

Weak Alfvénic turbulence in a periodic domain is considered as a mixed state of Alfvén waves interacting with the two-dimensional (2D) condensate. Unlike in standard treatments, no spectral continuity between the two is assumed, and, indeed, none is found. If the 2D modes are not directly forced, k−2 and k−1 spectra are found for the Alfvén waves and the 2D modes, respectively, with the latter less energetic than the former. The wave number at which their energies become comparable marks the transition to strong turbulence. For imbalanced energy injection, the spectra are similar, and the Elsasser ratio scales as the ratio of the energy fluxes in the counterpropagating Alfvén waves. If the 2D modes are forced, a 2D inverse cascade dominates the dynamics at the largest scales, but at small enough scales, the same weak and then strong regimes as described above are achieved

Impact of sulphur contamination on the performance of mixed ionic-electronic conducting membranes for oxygen separation and hydrogen production

PhD ThesisMixed ionic-electronic conducting (MIEC) membranes are a promising technology for oxygen separation but they are not commercialised yet due to sealing issue and sensitivity to impurities in feedstock. In this study, La0.6Sr0.4Co0.2Fe0.8O3- (LSCF6428) was successfully sealed for long-term operation of 963 h using a gold-glass-ceramic sealant. The membrane was then tested for air separation in presence of hydrogen sulphide for 100 h and results showed that the impurity caused a drop in oxygen flux to zero within few hours. The flux could not be fully restored after hydrogen sulphide removal and only 6 to 35% was recovered. It was proposed that hydrogen sulphide was adsorbed on the membrane in the form of sulphur and it occupied oxygen vacancies. With time, strontium segregates toward sulphur to form irreversible layer of strontium sulphate. To restore the damaged surface, the membrane was treated by 1% (mol) of hydrogen for 20 h and the recovery improved from 6 to 12%. It was discovered that the poisoning mechanism is a function of oxygen partial pressure and change of partial pressure from 0.21 to 0.01 bar resulted in 90% recovery and this can be used as a strategy to reduce the damage. The next step was to test the membrane for hydrogen production using 1% (mol) of methane and results showed that methane conversion was steady at 33% for 350 h. Methane oxidation was also carried in presence of hydrogen sulphide but it resulted in drop of conversion to 8%. However, the conversion was slowly regenerating with time and it reached a constant value of 15%. This recovery was interpreted by the reaction of methane with hydrogen sulphide or methane decomposition and the membrane acted as a catalyst for these reactions. After hydrogen sulphide removal from the feed, the conversion kept on decreasing and this was linked to the change of membrane properties and therefore the membrane could not provide the sites for methane-oxygen reaction. For better stability under hydrogen sulphide, the membrane was modified by adding a powder of LSCF6428 material over the dense membrane. This dual layer membrane was stable for air separation under hydrogen for 33 h and the flux was only reduced by 5%