9,518 research outputs found
Is CalPERS a Sovereign Wealth Fund?
Sovereign Wealth Funds (SWFs) are the subject of intense debate. While these funds are hard to define in precise terms, all agree they are government-sponsored pools of financial assets. With roughly 10 trillion in under a decade, many wonder what role these public investment funds will play in private markets. Due to SWFsí government sponsorship, some fear that they will be used illegitimately to advance political, instead of commercial, agendas. This geopolitical concern is compounded by a general lack of transparency and a perception among Western analysts of weak accountability and poor governance practices...
Sovereign Wealth Funds: Form and Function in the 21st Century
As representatives of nation-states in global financial markets, sovereign wealth funds (SWFs) share a common form and many functions. Arguably their form and functions owe as much to a shared (global) moment of institutional formation as they owe their form and functions to the hegemony of Anglo-American finance over the late 20th and early 21st centuries. We distinguish between the immediate future for SWFs in the aftermath of the global financial crisis, and two possible long-term scenarios; one of which sees SWFs becoming financial goliaths dominating global markets, while the other sees SWFs morphing into nation-state development institutions that intermediate between financial markets and the long-term commitments of the nation-state sponsors. If the former scenario dominates, global financial integration will accelerate with attendant costs and benefits. If the latter scenario dominates, SWFs are likely to differentiate and evolve, returning, perhaps, to their national traditions and their respective places in a world of contested power and influence. Here, we clarify the assumptions underpinning the conception and formation of sovereign wealth funds over the past twenty years or so in the face of the ‘new’ realities of global finance.Sovereign Wealth Funds, Crisis, Market Performance, Long-term Investment
Optimization approach for optical absorption in three-dimensional structures including solar cells
The rigorous coupled-wave approach (RCWA) and the differential evolution
algorithm (DEA) were coupled in a practicable approach to maximize absorption
in optical structures with three-dimensional morphology. As a model problem,
optimal values of four geometric parameters and the bandgaps of three i-layers
were found for an amorphous-silicon, multi-terminal, thin-film tandem solar
cell comprising three p-i-n junctions with a metallic hexagonally corrugated
back-reflector. When the optical short-circuit current density was chosen as
the figure of merit to be maximized, only the bandgap of the topmost i-layer
was significant and the remaining six parameters played minor roles. While this
configuration would absorb light very well, it would have poor electrical
performance. This is because the optimization problem allows for the
thicknesses and bandgaps of the semiconductor layers to change. We therefore
devised another figure of merit that takes into account bandgap changes by
estimating the open-circuit voltage. The resulting configuration was found to
be optimal with respect to all seven variable parameters. The RCWA+DEA
optimization approach is applicable to other types of photovoltaic solar cells
as well as optical absorbers, with the choice of the figure of merit being
vital to a successful outcome.Comment: 14 pages, 5 figure
Observing a Light CP-Violating Higgs Boson in Diffraction
Light CP-violating Higgs bosons with mass lower than 70 GeV might have
escaped detection in direct searches at the LEP collider. They may remain
undetected in conventional search channels at the Tevatron and LHC. In this
Letter we show that exclusive diffractive reactions may be able to probe for
the existence of these otherwise elusive Higgs particles. As a prototype
example, we calculate diffractive production cross-sections of the lightest
Higgs boson within the framework of the Minimal Supersymmetric Standard Model
with explicit CP violation. Our analysis shows that the challenging regions of
parameter space corresponding to a light CP-violating Higgs boson might be
accessible at the LHC provided suitable proton tagging detectors are installed.Comment: 9 pages, LaTeX, 2 figures, version as to appear in Phys. Rev.
Progress Towards Modeling the Ablation Response of NuSil-Coated PICA
The Mars Science Laboratory (MSL) Entry, Descent and Landing Instrumentation (MEDLI) collected in-flight data largely used by the ablation community to verify and validate physics-based models for the response of the Phenolic Impregnated Carbon Ablator (PICA) material [1-4]. MEDLI data were recently used to guide the development of NASAs high-fidelity material response models for PICA, implemented in the Porous material Analysis Toolbox based on OpenFOAM (PATO) software [5-6]. A follow-up instrumentation suite, MEDLI2, is planned for the upcoming Mars 2020 mission [7] after the large scientific impact of MEDLI. Recent analyses performed as part of MEDLI2 development draw the attention to significant effects of a protective coating to the aerothermal response of PICA. NuSil, a silicone-based overcoat sprayed onto the MSL heatshield as contamination control, is currently neglected in PICA ablation models. To mitigate the spread of phenolic dust from PICA, NuSil was applied to the entire MSL heatshield, including the MEDLI plugs. NuSil is a space grade designation of the siloxane copolymer, primarily used to protect against atomic oxygen erosion in the Low Earth Orbit environment. Ground testing of PICA-NuSil (PICA-N) models all exhibited surface temperature jumps of the order of 200 K due to oxide scale formation and subsequent NuSil burn-off. It is therefore critical to include a model for the aerothermal response of the coating in ongoing code development and validation efforts
HepData and JetWeb: HEP data archiving and model validation
The CEDAR collaboration is extending and combining the JetWeb and HepData
systems to provide a single service for tuning and validating models of
high-energy physics processes. The centrepiece of this activity is the fitting
by JetWeb of observables computed from Monte Carlo event generator events
against their experimentally determined distributions, as stored in HepData.
Caching the results of the JetWeb simulation and comparison stages provides a
single cumulative database of event generator tunings, fitted against a wide
range of experimental quantities. An important feature of this integration is a
family of XML data formats, called HepML.Comment: 4 pages, 0 figures. To be published in proceedings of CHEP0
On optical-absorption peaks in a nonhomogeneous thin-film solar cell with a two-dimensional periodically corrugated metallic backreflector
The rigorous coupled wave approach (RCWA) was implemented to investigate
optical absorption in a triple-p-i-n-junction amorphous-silicon solar cell with
a 2D metallic periodically corrugated backreflector (PCBR). Both total and
useful absorptances were computed against the free-space wavelength
for both s- and p-polarized polarization states. The useful absorptance in each
of the three p-i-n junctions was also computed for normal as well as oblique
incidence. Furthermore, two canonical boundary-value problems were solved for
the prediction of guided-wave modes (GWMs): surface-plasmon-polariton waves and
waveguide modes. Use of the doubly periodic PCBR enhanced both useful and total
absorptances in comparison to a planar backreflector. The predicted GWMs were
correlated with the peaks of the total and useful absorptances. The excitation
of GWMs was mostly confined to nm and enhanced absorption. As
excitation of certain GWMs could be correlated with the total absorptance but
not with the useful absorptance, the useful absorptance should be studied while
devising light-trapping strategies.Comment: 17 pages; 8 figure
Propellant Mass Fraction Calculation Methodology for Launch Vehicles and Application to Ares Vehicles
Propellant Mass Fraction (pmf) calculation methods vary throughout the aerospace industry. While typically used as a means of comparison between candidate launch vehicle designs, the actual pmf calculation method varies slightly from one entity to another. It is the purpose of this paper to present various methods used to calculate the pmf of launch vehicles. This includes fundamental methods of pmf calculation that consider only the total propellant mass and the dry mass of the vehicle; more involved methods that consider the residuals, reserves and any other unusable propellant remaining in the vehicle; and calculations excluding large mass quantities such as the installed engine mass. Finally, a historical comparison is made between launch vehicles on the basis of the differing calculation methodologies, while the unique mission and design requirements of the Ares V Earth Departure Stage (EDS) are examined in terms of impact to pmf
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