Results 71 to 80 of about 126,178 (307)

Approximations to the Performance of Wireless Optical Relaying Communications over Weak Turbulence Channels

open access: yesGuangtongxin yanjiu, 2021
Lognormal channel is a powerful mathematical tool in modeling fading effects for wireless optical communications over weak turbulence channels. However, exact analysis involving lognormal channels involves multi-fold integrals, which reveal little ...
Xiao CHEN, Xiao-ying HU
doaj   +1 more source

Beyond Zipf's Law: The Lavalette Rank Function and its Properties

open access: yes, 2016
Although Zipf's law is widespread in natural and social data, one often encounters situations where one or both ends of the ranked data deviate from the power-law function.
Cocho, Germinal   +4 more
core   +3 more sources

Comparison of lognormal population means [PDF]

open access: yesProceedings of the American Mathematical Society, 1994
Comparisons of two lognormal population means are investigated. For large samples, the conventional test for significance of the population means is the ordinary Student t-test with normal critical value. By Chen and Loh’s result (Ann. Statist. 20 (1992)), however, the transformed t-test based on log-data is asymptotically more powerful than the ...
openaire   +1 more source

Swedish Consumers' Willingness‐to‐Pay for Plant‐Based Proteins in Pasta Sauce: Preferences and Policy Scenarios

open access: yesAgribusiness, EarlyView.
ABSTRACT This paper explores Swedish consumers' protein preferences by estimating the willingness‐to‐pay (WTP) for minced meat and plant‐based proteins in pasta sauce from an in‐store experiment (n = 206) and an online discrete choice experiment (n = 517). On average, the WTP was highest for minced meat.
Emilia Mattsson   +3 more
wiley   +1 more source

Long-term survival rates of laryngeal cancer patients treated by radiation and surgery, radiation alone, and surgery alone : studied by lognormal and Kaplan-Meier survival methods

open access: yesBMC Cancer, 2005
Background Validation of the use of the lognormal model for predicting long-term survival rates using short-term follow-up data. Methods 907 cases of laryngeal cancer were treated from 1973–1977 by radiation and surgery (248), radiation alone (345), and ...
Shiels Ross   +3 more
doaj   +1 more source

Harnessing Digital Microstructure for Simulation‐Guided Optimization of Permanent Magnets

open access: yesAdvanced Intelligent Discovery, EarlyView.
An experimental‐to‐computational workflow is presented that transforms experimental 3D focused ion beam‐scanning electron microscopy data into a simulation‐ready digital microstructure for multiphase functional materials. Using heavy‐rare‐earth‐free Nd–Fe–B magnets as a model system, the approach quantifies grain connectivity across complex secondary ...
Nikita Kulesh   +4 more
wiley   +1 more source

Effect of confining pressure on fracture characteristics and mineralogical behavior of tight sandstone specimens after hydraulic fracturing

open access: yesDeep Underground Science and Engineering, EarlyView.
Hydraulic fracturing in tight sandstone and fracture propagation characteristics using backscattered electron‐scanning electron microscope (BSE‐SEM) images. Abstract This study focuses on hydraulic fracturing experiments conducted under triaxial conditions on tight sandstone specimens from Shivpuri district, Madhya Pradesh, India.
Pankaj Rawat, Narendra Kumar Samadhiya
wiley   +1 more source

parfm : Parametric Frailty Models in R

open access: yesJournal of Statistical Software, 2012
Frailty models are getting more and more popular to account for overdispersion and/or clustering in survival data. When the form of the baseline hazard is somehow known in advance, the parametric estimation approach can be used advantageously ...
Marco Munda   +2 more
doaj  

Weibull or Lognormal Distribution to Characterize Fatigue Life Scatter – Which is More Suitable? – Continued

open access: yesFatigue of Aircraft Structures
This paper describes a study to determine whether fatigue test life scatter is best characterised by a Weibull or lognormal statistical distribution for a high strength steel used for landing gear structures. It is a response to “Face 2” of the ICAF 2017
Plaskitt Rob   +2 more
doaj   +1 more source

Data‐driven analysis of the spatial dependence of grouting efficiency during tunnel excavation

open access: yesDeep Underground Science and Engineering, EarlyView.
Prediction of grouting efficiency using machine learning is enhanced by adopting a training strategy that accounts for the grouting process across multiple rounds. Abstract Grouting with water–cement mixtures is the most widely used and cost‐effective method for managing excess water inflow during tunnel construction.
Huaxin Liu, Xunchang Fei, Wei Wu
wiley   +1 more source

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