4,107 research outputs found
A quantum jump description for the non-Markovian dynamics of the spin-boson model
We derive a time-convolutionless master equation for the spin-boson model in
the weak coupling limit. The temporarily negative decay rates in the master
equation indicate short time memory effects in the dynamics which is explicitly
revealed when the dynamics is studied using the non-Markovian jump description.
The approach gives new insight into the memory effects influencing the spin
dynamics and demonstrates, how for the spin-boson model the the co-operative
action of different channels complicates the detection of memory effects in the
dynamics.Comment: 9 pages, 6 figures, submitted to Proceedings of CEWQO200
FINGERPRINT RECOGNITION SYSTEM
This project is to design a fingerprint recognition system for security purposes. It will
also explore and suggest some solution to the improvement to the existing fingerprint system.
Security system that uses a pin code or access card can be easily misused or mishandled. A pin
code can be cracked using some hacker software while an access card can easily be stolen or
misplaced. Thus, these security methods are very vulnerable to hackers and criminals. Instead, a
fingerprint is unique to every person and due to the fact that no two people have the same
fingerprint pattern, it makes the fingerprint a very good resource in a security system.
The aim of this project is to focus on the concept and methodology of the fingerprint
recognition system. By grasping the concept and method of the fingerprint recognition flow, a
prototype is developed that will compare an input fingerprint with its predefined template. The
system should be able to compare and decide if the input fingerprint is the same as the
predefined template.
The output of the first stage is a preprocessing stage. There are two stages involved in
preprocessing which is the image enhancement and image skeletonization. Fourier transfonn and
histogram equalization is utilized to enhance the low quality image to a better image so that the
feature extraction process will run smoothly.
The second stage of the project is to define the orientation, ROI extraction and minutia
extraction. The matching sequence and the angle orientation problem were resolved
Determination of the weak Hamiltonian in the SU(4) chiral limit through topological zero-mode wave functions
A new method to determine the low-energy couplings of the weak
Hamiltonian is presented. It relies on a matching of the topological poles in
of three-point correlators of two pseudoscalar densities and a
four-fermion operator, measured in lattice QCD, to the same observables
computed in the -regime of chiral perturbation theory. We test this
method in a theory with a light charm quark, i.e. with an SU(4) flavour
symmetry. Quenched numerical measurements are performed in a 2 fm box, and
chiral perturbation theory predictions are worked out up to next-to-leading
order. The matching of the two sides allows to determine the weak low-energy
couplings in the SU(4) limit. We compare the results with a previous
determination, based on three-point correlators containing two left-handed
currents, and discuss the merits and drawbacks of the two procedures.Comment: 38 pages, 9 figure
Weak low-energy couplings from topological zero-mode wavefunctions
We discuss a new method to determine the low-energy couplings of the weak Hamiltonian in the -regime. It relies on a matching of the
topological poles in of three-point functions of two pseudoscalar
densities and a four-fermion operator computed in lattice QCD, to the same
observables in the Chiral Effective Theory. We present the results of a NLO
computation in chiral perturbation theory of these correlation functions
together with some preliminary numerical results.Comment: 7 pages. Contribution to Lattice 200
Thermodynamics of the QCD plasma and the large-N limit
The equilibrium thermodynamic properties of the SU(N) plasma at finite
temperature are studied non-perturbatively in the large-N limit, via lattice
simulations. We present high-precision numerical results for the pressure,
trace of the energy-momentum tensor, energy density and entropy density of
SU(N) Yang-Mills theories with N=3, 4, 5, 6 and 8 colors, in a temperature
range from 0.8T_c to 3.4T_c (where T_c denotes the critical deconfinement
temperature). The results, normalized according to the number of gluons, show a
very mild dependence on N, supporting the idea that the dynamics of the
strongly-interacting QCD plasma could admit a description based on large-N
models. We compare our numerical data with general expectations about the
thermal behavior of the deconfined gluon plasma and with various theoretical
descriptions, including, in particular, the improved holographic QCD model
recently proposed by Kiritsis and collaborators. We also comment on the
relevance of an AdS/CFT description for the QCD plasma in a phenomenologically
interesting temperature range where the system, while still strongly-coupled,
approaches a `quasi-conformal' regime characterized by approximate scale
invariance. Finally, we perform an extrapolation of our results to the N to
limit.Comment: 1+38 pages, 13 eps figures; v2: added reference
Meeting Global Cooling Demand with Photovoltaics during the 21st Century
Space conditioning, and cooling in particular, is a key factor in human
productivity and well-being across the globe. During the 21st century, global
cooling demand is expected to grow significantly due to the increase in wealth
and population in sunny nations across the globe and the advance of global
warming. The same locations that see high demand for cooling are also ideal for
electricity generation via photovoltaics (PV). Despite the apparent synergy
between cooling demand and PV generation, the potential of the cooling sector
to sustain PV generation has not been assessed on a global scale. Here, we
perform a global assessment of increased PV electricity adoption enabled by the
residential cooling sector during the 21st century. Already today, utilizing PV
production for cooling could facilitate an additional installed PV capacity of
approximately 540 GW, more than the global PV capacity of today. Using
established scenarios of population and income growth, as well as accounting
for future global warming, we further project that the global residential
cooling sector could sustain an added PV capacity between 20-200 GW each year
for most of the 21st century, on par with the current global manufacturing
capacity of 100 GW. Furthermore, we find that without storage, PV could
directly power approximately 50% of cooling demand, and that this fraction is
set to increase from 49% to 56% during the 21st century, as cooling demand
grows in locations where PV and cooling have a higher synergy. With this
geographic shift in demand, the potential of distributed storage also grows. We
simulate that with a 1 m water-based latent thermal storage per household,
the fraction of cooling demand met with PV would increase from 55% to 70%
during the century. These results show that the synergy between cooling and PV
is notable and could significantly accelerate the growth of the global PV
industry
Meeting Global Cooling Demand with Photovoltaics during the 21st Century
Space conditioning, and cooling in particular, is a key factor in human
productivity and well-being across the globe. During the 21st century, global
cooling demand is expected to grow significantly due to the increase in wealth
and population in sunny nations across the globe and the advance of global
warming. The same locations that see high demand for cooling are also ideal for
electricity generation via photovoltaics (PV). Despite the apparent synergy
between cooling demand and PV generation, the potential of the cooling sector
to sustain PV generation has not been assessed on a global scale. Here, we
perform a global assessment of increased PV electricity adoption enabled by the
residential cooling sector during the 21st century. Already today, utilizing PV
production for cooling could facilitate an additional installed PV capacity of
approximately 540 GW, more than the global PV capacity of today. Using
established scenarios of population and income growth, as well as accounting
for future global warming, we further project that the global residential
cooling sector could sustain an added PV capacity between 20-200 GW each year
for most of the 21st century, on par with the current global manufacturing
capacity of 100 GW. Furthermore, we find that without storage, PV could
directly power approximately 50% of cooling demand, and that this fraction is
set to increase from 49% to 56% during the 21st century, as cooling demand
grows in locations where PV and cooling have a higher synergy. With this
geographic shift in demand, the potential of distributed storage also grows. We
simulate that with a 1 m water-based latent thermal storage per household,
the fraction of cooling demand met with PV would increase from 55% to 70%
during the century. These results show that the synergy between cooling and PV
is notable and could significantly accelerate the growth of the global PV
industry
Intensive big room process for co-creating value in legacy construction projects
In construction projects the changes and refinements of client requirements are often seen just as a disturbance causing additional costs. However, today clients' business needs evolve constantly and therefore changes in the project requirements are inevitable. Simultaneously, the increasing competition forces companies to minimise unproductive capital costs. Therefore there is an economical pressure to shorten the construction time and the design and construction will be even more concurrent than today. There is clearly potential value to be created for customer by terms of collaborative design process. Fira is an innovative Finnish company which has developed its interactive and customer centric Verstas process since 2009. Fira is using service logic as a guiding principle in the development of collaborative design processes, such as Intensive Big Room (IBR), which is a combination of Building Information Modelling (BIM) and further development of Integrated Concurrent Engineering (ICE ) and Big Room methodologies. The traditional project management methods are not efficient in managing late changes in customer's requirements. This article presents a new method combining collaborative design process, requirements management and IBR in a small sub-process - locking and ironmongery - in legacy construction project models. The sub-process was selected for the development of the method because it is a perfect example of the traditional fragmented process where efficient coordination between different participants and management of requirements are very difficult. However, the same principles can be applied to many other sub-processes too. The method combines service logic, value co-creation and use of IBR concept in a standard contract environment in a unique way which can give significant benefits to the companies able to adopt the presented concept in their business models. Using these methods Fira can now change its business model, differentiate with more attractive value proposal for customer, create more value than its competitors and capture value for securing its competitiveness in future
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