PDU with Integrated Cable Management Support

Cable management within a datacenter rack has become critical as rack densities continue to increase, and additional quantities of Power Distribution Units (PDU) are being installed in a rack thus resulting in less area to route and secure cables. A standard 1075mm deep rack has one PDU mounting bracket per side to mount vertical PDUs which often also gets utilized for cable management, and in some circumstances cables are even secured to the rack frame members

CBR Properties of Sand Mixed with Modified Waste Expanded Polystyrene Foams (EPS)

The impact of using recycled waste expanded polystyrene foams (EPS), as a lightweight fill material by mixing with river sand were presented in this study. The waste EPS were thermally modified. The modified expanded polystyrene (MEPS) were gained by putting the waste EPS into an oven at 130°C for 15 minutes. The California Bearing Ratio (CBR) values of sand mixed with MEPS was studied. To conduct the test, five series of specimens were prepared that have a replacement of MEPS by weight which were 0%, 5%, 10%, 15%, and 20%. For each ratio CBR test were conducted. Unsoaked condition was used to perform the tests. By increasing the percentage of MEPS the values of CBR of the mixture were decreased. However, the minimum CBR value at 20% MEPS is still within subbase tolerance. Results of the tests demonstrate that addition of 20 % MEPS in sand makes the reduction of the density of mixture almost 50 %. MEPS can be an alternative light weight fill material for geotechnical application such as embankment of abutment

Variational Derivation of Relativistic Fermion-Antifermion Wave Equations in QED

We present a variational method for deriving relativistic two-fermion wave equations in a Hamiltonian formulation of QED. A reformulation of QED is performed, in which covariant Green functions are used to solve for the electromagnetic field in terms of the fermion fields. The resulting modified Hamiltonian contains the photon propagator directly. The reformulation permits one to use a simple Fock-space variational trial state to derive relativistic fermion-antifermion wave equations from the corresponding quantum field theory. We verify that the energy eigenvalues obtained from the wave equation agree with known results for positronium.Comment: 25 pages, accepted in Journal of Mathematical Physics (2004

Heave Failure as a Fourth Type of Seepage-Induced Internal Instability Problems Associated With Granular Soils

Internal instability problems associated with granular soils involves washing out of the fine grains within the voids of the coarse grains. This movement may involve one or more of the following, mass loss, volume change, and permeability change. Leading to the occurrence of one of these possible cases, namely, suffusion (involves mass loss with no volume change), suffusion (involves mass lose with volume reduction), fluidization (involves volume change without mass loss). These three cases are well defined in the literatures; however the authors of this paper have found a fourth case (heave failure) was not taken in consideration. Heave failure involves both mass lose and increment in volume of the granular soil. Deep understanding of this case will prevent failure of geotechnical and hydraulic structures. Here in this paper the conditions that lead to the occurrence of heave failure are defined and illustration is made based on some experimental studies. Also it is found that the applied stresses on the soil can change the mode of internal instability failure from suffusion to suffusion / suffusion failure mode. editor

Exact spinor-scalar bound states in a QFT with scalar interactions

We study two-particle systems in a model quantum field theory, in which scalar particles and spinor particles interact via a mediating scalar field. The Lagrangian of the model is reformulated by using covariant Green's functions to solve for the mediating field in terms of the particle fields. This results in a Hamiltonian in which the mediating-field propagator appears directly in the interaction term. It is shown that exact two-particle eigenstates of the Hamiltonian can be determined. The resulting relativistic fermion-boson equation is shown to have Dirac and Klein-Gordon one-particle limits. Analytic solutions for the bound state energy spectrum are obtained for the case of massless mediating fields.Comment: 12 pages, RevTeX, 1 figur

Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics

Global forage-fish landings are increasing, with potentially grave consequences for marine ecosystems. Predators of forage fish may be influenced by this harvest, but the nature of these effects is contentious. Experimental fishery manipulations offer the best solution to quantify population-level impacts, but are rare. We used Bayesian inference to examine changes in chick survival, body condition and population growth rate of endangered African penguins Spheniscus demersus in response to 8 years of alternating time–area closures around two pairs of colonies. Our results demonstrate that fishing closures improved chick survival and condition, after controlling for changing prey availability. However, this effect was inconsistent across sites and years, highlighting the difficultly of assessing management interventions in marine ecosystems. Nevertheless, modelled increases in population growth rates exceeded 1% at one colony; i.e. the threshold considered biologically meaningful by fisheries management in South Africa. Fishing closures evidently can improve the population trend of a forage-fish-dependent predator—we therefore recommend they continue in South Africa and support their application elsewhere. However, detecting demographic gains for mobile marine predators from small no-take zones requires experimental time frames and scales that will often exceed those desired by decision makers

The role of management support for the implementation of open innovation practices in firms

Open innovation (OI) has gained a lot of popularity in the last decade, as sharing research and innovation efforts offer several benefits for firms and industries. However, implementing a successful OI environment within firms has several internal and external challenges. Therefore, researchers are investigating the factors that might contribute to achieving a successful OI adoption. This paper investigates the effect of management support on the successful adoption of OI. The paper uses regression techniques with data from an OI survey that was conducted in Europe in 2014. Respondents, from several countries and industries, were asked to evaluate their firm's current OI adoption level, as well as, several internal competencies. The dataset analysis results showed that there is a positive correlation between management support of OI and the possibility of successful adoption of OI. Moreover, the results offered insight on some of the dynamics of how management support affect OI adoption

Optimum Location And Bracing System As Alternative To Shear Walls For Retrofitting Of RC Buildings Against Seismic Loading

The defective structures must be retrofitted to resist the effects of earthquakes due to the potential risks connected with reinforced concrete structures designed in many parts of the world in accordance with codes that are now proven to guarantee insufficient safety against seismic loads. Typically, shear walls or steel bracing are utilized to boost the seismic strength of framed structures. This paper discusses the possibility of using braces in two different conditions, the first one is in retrofitting already constructed structures that don’t have sufficient strength against seismic loading, and the second one is the possibility of using braces instead of shear walls in designing non constructed reinforced concrete structures for economical purposes. Different bracing systems in different locations compared with reinforced concrete shear walls in affecting the structural properties of the 10-story square building. Using bracing in the interior frames of buildings was also considered. The results show that different bracing systems have different responses for structural properties such as story displacement, base shear and fundamental time period. The results are significant for detecting the best bracing system to use instead of shear walls reflecting for the two mentioned scenarios as well as considering their locations on the building

Math teachers' beliefs, practices, and belief change in implementing problem based learning in Qatari primary governmental school

This study explored math teachers' beliefs regarding their roles, practices and perceived change in implementing Problem-Based Learning in Qatar's primary government schools. Multiple sources of qualitative data were generated including metaphors, lesson plans and interviews with seventeen math teachers. Although teachers considered PBL as an effective method benefiting student learning and they demonstrated progress in changing their beliefs moving from subject to didactic dimension through PBL implementation, their practices remained partially aligned with their perceived belief changes. This discrepancy could be attributed to several encountered challenges, including teachers' insecurity and lack of confidence, difficulty in facilitating student collaboration, structural constraints, additional workload, and the lack of school and peer support. Results suggest the need for different types of "problems" and approaches such as more direct instruction, and higher feasibility in teachers' autonomy when implementing PBL in primary education.Scopu