Search results for "Partial"
showing 10 items of 1477 documents
A Perturbation Approach to Continuous-Time Portfolio Selection Under Stochastic Investment Opportunities
2013
This paper studies portfolio selection in continuous-time models with stochastic investment opportunities. We consider asset allocation problems where preferences are specified as power utility derived from terminal wealth as well as consumption-savings problems with recursive utility Epstein-Zin preferences. The paper approximates the associated dynamic programming problem by perturbing the coefficients of the stochastic dynamics. We represent the Hamilton-Jacobi-Bellman equation as a series of partial differential equations that can be solved iteratively in closed-form through computer algebra software, at any desired accuracy.
Characterization of pre-treatments on wood chips prior to delignification by near infrared spectroscopy
2017
A near infrared (NIR) spectroscopy-based method for predicting yields and lignin contents of differently pre-treated silver/white birch (Betula pendula/B. pubescens) and Scots pine (Pinus sylvestris) chips was developed. The approach was to create multivariate calibration models from the NIR data by the partial least squares (PLS) method. Both parameters are important factors when adjusting adequate conditions for pre-treatments either with hot-water (HW) as such and slightly acidified HW (collectively referred to as autohydrolysis) or dilute alkaline aqueous solutions prior to alkaline pulping. Pre-treatment conditions were varied with respect to temperature (130 °C and 150 °C) and treatme…
Comparison of parallel implementation of some multi-level Schwarz methods for singularly perturbed parabolic problems
1999
Abstract Parallel multi-level algorithms combining a time discretization and an overlapping domain decomposition technique are applied to the numerical solution of singularly perturbed parabolic problems. Two methods based on the Schwarz alternating procedure are considered: a two-level method with auxiliary “correcting” subproblems as well as a three-level method with auxiliary “predicting” and “correcting” subproblems. Moreover, modifications of the methods using time extrapolation on subdomain interfaces are investigated. The emphasis is given to the description of the algorithms as well as their computer realization on a distributed memory multiprocessor computer. Numerical experiments …
The effect of Transient over Voltages on the Partial Discharges activity in HVDC joints
2021
Rapid growth of HVDC cable line installations is expected in the coming years. Several research groups have investigated dielectric phenomena that occur in the insulation of HVDC cables and accessories that accelerate aging and reduce the reliability of this technology over time. Unlike in HVAC cables, under HVDC stress, the distribution of the electric field inside the insulation layer depends not only on the applied voltage but also on the temperature distribution and on other factors related to manufacturing such as the presence of impurities. Reaching local and transient electric field peaks can enhance the onset of Partial Discharges (PDs) which can lead to premature aging of the insul…
An Importance-Performance Matrix Analysis of the Factors Influencing US Tourists to Use Airbnb
2019
After 10 years of Airbnb and its significant growth, this research is conducted to identify which factors really matter to Airbnb users today. It provides an integrated approach, since it aggregates factors that other studies have considered separately. With a sample of 101 US respondents, the partial least squares structural equation modelling results evidence that the only factors that influence future intentions to use Airbnb are its unique and varied accommodations and satisfaction. Enjoyment was also found to have a positive effect on Satisfaction. The study further investigates these factors with an Importance Performance map, providing guidance for the prioritization of managerial ac…
Synthesis and support composition effects on CH4 partial oxidation over Ni–CeLa oxides
2015
Abstract Two series of Ni (6 wt%) catalysts supported over CeO 2 , La 2 O 3 and mixed CeO 2 –La 2 O 3 were prepared by co-precipitation and by wet-impregnation. The effect of the two Ni loading procedures on the catalyst structural properties was investigated by XRD, TPR and XPS. The catalytic behavior of the catalysts was tested in the methane partial oxidation reaction performed at 1 atm in a temperature range of 400–800 °C using dilute feed gas mixture with CH 4 /O 2 = 2 and gas hourly space velocity of 60,000 ml g −1 h −1 . Total methane combustion was observed within the 450 °C ≤ T ≤ 650 °C temperature range. Above 650 °C partial oxidation of methane started to occur, reaching at 80…
Sensitivity analysis of efficiency and Malmquist productivity indices: An application to Spanish savings banks
2008
Hypothesis testing and statistical precision in the context of non-parametric efficiency and productivity measurement have been investigated since the early 1990s. Recent contributions focus on this matter through the use of resampling methods-i.e., bootstrapping techniques. However, empirical evidence is still practically non-existent. This gap is more noticeable in the case of banking efficiency studies, where the literature is immense. In this work, we explore productivity growth and productive efficiency for Spanish savings banks over the (initial) post-deregulation period 1992-1998 using Data Envelopment Analysis (DEA) and bootstrapping techniques. Results show that productivity growth…
SrTiO 3 -based perovskites: Preparation, characterization and photocatalytic activity in gas–solid regime under simulated solar irradiation
2015
Strontium titanate-based perovskites have been prepared in the presence of Y and Co with the aim to substitute Sr and Ti, respectively, in the ST crystalline structure. The obtained samples have been characterized by XRD, Raman spectroscopy, FE-SEM, XPS and tested as photocatalysts in two gas-solid regime reactions: (i) 2-propanol complete mineralization and (ii) propene partial oxidation, using a system simulating solar irradiation. All the tested samples resulted active as photocatalysts but with significant differences. The lattice substitution of Sr by Y displays a beneficial effect on the 2-propanol photodegradation. Conversely, the partial presence of cobalt on the ST surface, as Co-o…
Selective oxidation of C3–C4 olefins over Mo-containing catalysts with tetragonal tungsten bronze structure
2009
Abstract Mo–V–Nb–P–O-based catalysts with a tetragonal tungsten bronze-type (TTB) structure have been prepared hydrothemally from a H 3 PMo 12 O 40 Keggin-type heteropolyacid. These catalysts have been tested in the oxidation of C 3 –C 4 olefins (propene, isobutene and 1-butene). Although the catalytic performance depends on the nature of the olefin fed the TTB-type catalysts prepared in the presence of elements of the V and VI groups such as Te, Sb and Bi have shown a high selectivity to partial oxidation products, especially that with Te. However, in the absence of these elements the TTB-catalysts present a high catalytic activity to deep oxidation. The selectivity to partial oxidation pr…
Analysis of fit on implants of chrome cobalt versus titanium frameworks made by cad / cam milling
2020
Background This study analyzed the degree of passive and vertical fit achieved in frameworks using either cobalt-chromium (Co-Cr) or titanium (Ti) implant-supported fixed partial dentures ( FPDs) fabricated with a CAD/CAM milling technique. Material and Methods 33 3-unit FDPs, 17 of Co-Cr metal alloy (test group) and 16 of Ti (control group), were manufactured with two implants by copy milled technology. Optical microscopy was used to measure passive fit (PF) and vertical fit (VF) in all frameworks. The PF was evaluated by using the Single Screw test and the VF with the screws tightened at 20 Ncm. Descriptive and inferential analysis were performed to evaluate statistically significant diff…