718 research outputs found
Reduction of spurious velocity in finite difference lattice Boltzmann models for liquid - vapor systems
The origin of the spurious interface velocity in finite difference lattice
Boltzmann models for liquid - vapor systems is related to the first order
upwind scheme used to compute the space derivatives in the evolution equations.
A correction force term is introduced to eliminate the spurious velocity. The
correction term helps to recover sharp interfaces and sets the phase diagram
close to the one derived using the Maxwell construction.Comment: 22 pages, 10 figures (submitted to International Journal of Modern
Physics C- Physics and Computers
Reuse patterns in adaptation languages : creating a meta-level for the LAG adaptation language
A growing body of research targets authoring of content and adaptation strategies for adaptive systems. The driving force behind it is semantics-based reuse: the same strategy can be used for various domains, and vice versa. Whilst using an adaptation language (LAG e.g.) to express reusable adaptation strategies, we noticed, however, that: a) the created strategies have common patterns that, themselves, could be reused; b) templates based on these patterns could reduce the designers' work; c) there is a strong preference towards XML-based processing and interfacing. This has leaded us to define a new meta-language for LAG, extracting common design patterns. This paper provides more insight into some of the limitations of Adaptation Languages like LAG, as well as describes our meta-language, and shows how introducing the meta-level can overcome some redundancy issues
Adaptive hypermedia system interoperability : a 'real world' evaluation
Adaptive Hypermedia (AH) authoring is widely acknowledged to be complex and time consuming, yet this vital process is rarely evaluated. Recent research has approached the authoring problem by ensuring that previously created materials can be converted from one system to another. This paper evaluates the results of this research, specifically the creation of adaptive materials in MOT and their conversion and subsequent delivery in WHURLE. A group of technically experienced IT users who are novice AH authors were exposed to MOT and WHURLE during an introductory week long course. This paper interprets the results of these authors using a "write once, deliver many" paradigm of adaptive hypermedia creation
On the number of solutions of a transcendental equation arising in the theory of gravitational lensing
The equation in the title describes the number of bright images of a point
source under lensing by an elliptic object with isothermal density. We prove
that this equation has at most 6 solutions. Any number of solutions from 1 to 6
can actually occur.Comment: 26 pages, 12 figure
A Phase 1b Study of Humanized Ks-Interleukin-2 (Huks-Il2) Immunocytokine with Cyclophosphamide in Patients with Epcam-Positive Advanced Solid Tumors
BackgroundHumanized KS-interleukin-2 (huKS-IL2), an immunocytokine with specificity for epithelial cell adhesion molecule (EpCAM), has demonstrated favorable tolerability and immunologic activity as a single agent.MethodsPhase 1b study in patients with EpCAM-positive advanced solid tumors to determine the maximum tolerated dose (MTD) and safety profile of huKS-IL2 in combination with low-dose cyclophosphamide. Treatment consisted of cyclophosphamide (300mg/m2 on day 1), and escalating doses of
Lattice Boltzmann study on Kelvin-Helmholtz instability: the roles of velocity and density gradients
A two-dimensional lattice Boltzmann model with 19 discrete velocities for
compressible Euler equations is proposed (D2V19-LBM). The fifth-order Weighted
Essentially Non-Oscillatory (5th-WENO) finite difference scheme is employed to
calculate the convection term of the lattice Boltzmann equation. The validity
of the model is verified by comparing simulation results of the Sod shock tube
with its corresponding analytical solutions. The velocity and density gradient
effects on the Kelvin-Helmholtz instability (KHI) are investigated using the
proposed model. Sharp density contours are obtained in our simulations. It is
found that, the linear growth rate for the KHI decreases with
increasing the width of velocity transition layer but increases with
increasing the width of density transition layer . After the
initial transient period and before the vortex has been well formed, the linear
growth rates, and , vary with and
approximately in the following way, and
, where , ,
and are fitting parameters and is the effective
interaction width of density transition layer. When
the linear growth rate does not vary significantly any more.
One can use the hybrid effects of velocity and density transition layers to
stabilize the KHI. Our numerical simulation results are in general agreement
with the analytical results [L. F. Wang, \emph{et al.}, Phys. Plasma
\textbf{17}, 042103 (2010)].Comment: Accepted for publication in PR
RESEARCHES ON THE INFLUENCE OF RISKS IN INDUSTRIAL ORGANIZATIONS’ PROCESSES WHEN IMPLEMENTING QUALITY-RISK INTEGRATED MANAGEMENT SYSTEMS
The concept of the integrated quality-risk management system can be defined as a set of methodologies, associated processes that invariably use human resources, material and financial resources, equipments and knowledge, in order to meet the objectives aimed at satisfying all interested parties.In the conditions of fulfilling the integrated management system, it will bring many economic and financial benefits in order to reduce the consumption of resources and increase the profit. If implemented correctly, the quality-risk integrated management system will include all business competencies in a systematic environment that will deliver on the mission of the organization, contribute to increasing benefits, optimize resource consumption, and reduce costs to maintain multiple integrated management systems
Dynamic modelling and nonlinear model predictive control of a fluid catalytic cracking unit
The paper presents the application of two nonlinear model predictive control (NMPC) approaches: quasi-infinite-horizon nonlinear MPC (QIHNMPC) and moving horizon estimator nonlinear MPC (MHE-NMPC) to the Fluid Catalytic Cracking Unit (FCCU). A complex dynamic model of the reactor–regenerator–fractionator system is developed and subsequently used in the controller. The novelty of the model consists in that besides the complex dynamics of the reactor–regenerator system, it also includes the dynamic model of the fractionator, as well as a five lumps kinetic model for the riser. Tight control is achieved using the QIHNMPC approach. The MHE-NMPC considers important features of a real-time control algorithm, resulting in a framework for practical NMPC implementation, such as: state and parameter estimation and efficient solution of the optimisation problem. In the NMPC approach, only measurements available in practice are considered, whereas the rest of the states are estimated together with uncertain model parameters, via MHE technique. Using an efficient numerical implementation based on the multiple shooting algorithm real-time feasibility of the approach is achieved. The incentives of the proposed approaches are assessed on the simulated industrial FCCU
Data sharing and reanalysis of randomized controlled trials in leading biomedical journals with a full data sharing policy: survey of studies published in the BMJ and PLOS Medicine
Objectives To explore the effectiveness of data sharing by randomized controlled trials (RCTs) in journals with a full data sharing policy and to describe potential difficulties encountered in the process of performing reanalyses of the primary outcomes. Design Survey of published RCTs. Setting PubMed/Medline. Eligibility criteria RCTs that had been submitted and published by The BMJ and PLOS Medicine subsequent to the adoption of data sharing policies by these journals. Main outcome measure The primary outcome was data availability, defined as the eventual receipt of complete data with clear labelling. Primary outcomes were reanalyzed to assess to what extent studies were reproduced. Difficulties encountered were described. Results 37 RCTs (21 from The BMJ and 16 from PLOS Medicine) published between 2013 and 2016 met the eligibility criteria. 17/37 (46%, 95% confidence interval 30% to 62%) satisfied the definition of data availability and 14 of the 17 (82%, 59% to 94%) were fully reproduced on all their primary outcomes. Of the remaining RCTs, errors were identified in two but reached similar conclusions and one paper did not provide enough information in the Methods section to reproduce the analyses. Difficulties identified included problems in contacting corresponding authors and lack of resources on their behalf in preparing the datasets. In addition, there was a range of different data sharing practices across study groups. Conclusions Data availability was not optimal in two journals with a strong policy for data sharing. When investigators shared data, most reanalyses largely reproduced the original results. Data sharing practices need to become more widespread and streamlined to allow meaningful reanalyses and reuse of data
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