scholarly journals Regularization of inverse problems by an approximate matrix-function technique

2021 ◽  
Author(s):  
Stefano Cipolla ◽  
Marco Donatelli ◽  
Fabio Durastante
Keyword(s):  
Matrix Function ◽  
Krylov Subspace ◽  
Step Function ◽  
Function Technique ◽  
Benchmark Problems ◽  
Regular Approximation ◽  
Regularization Techniques ◽  
Ill Posed ◽  
The One ◽  
High Level

AbstractIn this work, we introduce and investigate a class of matrix-free regularization techniques for discrete linear ill-posed problems based on the approximate computation of a special matrix-function. In order to produce a regularized solution, the proposed strategy employs a regular approximation of the Heavyside step function computed into a small Krylov subspace. This particular feature allows our proposal to be independent from the structure of the underlying matrix. If on the one hand, the use of the Heavyside step function prevents the amplification of the noise by suitably filtering the responsible components of the spectrum of the discretization matrix, on the other hand, it permits the correct reconstruction of the signal inverting the remaining part of the spectrum. Numerical tests on a gallery of standard benchmark problems are included to prove the efficacy of our approach even for problems affected by a high level of noise.

Relations between carbon removal rates, biofilm size and density of a novel anaerobic reactor: the inverse turbulent bed

2000 ◽  
Vol 41 (4-5) ◽  
pp. 253-260 ◽  
Author(s):  
P. Buffière ◽  
R. Moletta
Keyword(s):  
Removal Rate ◽  
Removal Rates ◽  
Carbon Removal ◽  
Biofilm Growth ◽  
Loading Rates ◽  
Biomass Activity ◽  
High Turbulence ◽  
The One ◽  
High Level ◽  
Very High

An anaerobic inverse turbulent bed, in which the biogas only ensures fluidisation of floating carrier particles, was investigated for carbon removal kinetics and for biofilm growth and detachment. The range of operation of the reactor was kept within 5 and 30 kgCOD· m−3· d−1, with Hydraulic Retention Times between 0.28 and 1 day. The carbon removal efficiency remained between 70 and 85%. Biofilm size were rather low (between 5 and 30 μm) while biofilm density reached very high values (over 80 kgVS· m−3). The biofilm size and density varied with increasing carbon removal rates with opposite trends; as biofilm size increases, its density decreases. On the one hand, biomass activity within the reactor was kept at a high level, (between 0.23 and 0.75 kgTOC· kgVS· d−1, i.e. between 0.6 and 1.85 kgCOD·kgVS · d−1).This result indicates that high turbulence and shear may favour growth of thin, dense and active biofilms. It is thus an interesting tool for biomass control. On the other hand, volatile solid detachment increases quasi linearly with carbon removal rate and the total amount of solid in the reactor levels off at high OLR. This means that detachment could be a limit of the process at higher organic loading rates.

scholarly journals Some transpose-free CG-like solvers for nonsymmetric ill-posed problems

2020 ◽  
Vol 28 (1) ◽  
pp. 15-32
Author(s):  
Silvia Gazzola ◽  
Paolo Novati
Keyword(s):  
Krylov Subspace ◽  
Main Idea ◽  
System Matrix ◽  
Numerical Tests ◽  
New Methods ◽  
Arnoldi Algorithm ◽  
Ill Posed ◽  
Efficient Alternative ◽  
Original Class ◽  
Theoretical Insight

AbstractThis paper introduces and analyzes an original class of Krylov subspace methods that provide an efficient alternative to many well-known conjugate-gradient-like (CG-like) Krylov solvers for square nonsymmetric linear systems arising from discretizations of inverse ill-posed problems. The main idea underlying the new methods is to consider some rank-deficient approximations of the transpose of the system matrix, obtained by running the (transpose-free) Arnoldi algorithm, and then apply some Krylov solvers to a formally right-preconditioned system of equations. Theoretical insight is given, and many numerical tests show that the new solvers outperform classical Arnoldi-based or CG-like methods in a variety of situations.

scholarly journals Parsimonious Predictive Mortality Modeling by Regularization and Cross-Validation with and without Covid-Type Effect

Risks ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 5
Author(s):  
Karim Barigou ◽  
Stéphane Loisel ◽  
Yahia Salhi
Keyword(s):  
Life Insurance ◽  
Cross Validation ◽  
Cohort Effect ◽  
Information Criterion ◽  
Mortality Forecasting ◽  
Hand Model ◽  
Regularization Techniques ◽  
Bayes Information Criterion ◽  
The One ◽  
Regularized Model

Predicting the evolution of mortality rates plays a central role for life insurance and pension funds. Standard single population models typically suffer from two major drawbacks: on the one hand, they use a large number of parameters compared to the sample size and, on the other hand, model choice is still often based on in-sample criterion, such as the Bayes information criterion (BIC), and therefore not on the ability to predict. In this paper, we develop a model based on a decomposition of the mortality surface into a polynomial basis. Then, we show how regularization techniques and cross-validation can be used to obtain a parsimonious and coherent predictive model for mortality forecasting. We analyze how COVID-19-type effects can affect predictions in our approach and in the classical one. In particular, death rates forecasts tend to be more robust compared to models with a cohort effect, and the regularized model outperforms the so-called P-spline model in terms of prediction and stability.

scholarly journals Testing Todd: family types and development

2021 ◽  
pp. 1-18
Author(s):  
Jerg Gutmann ◽  
Stefan Voigt
Keyword(s):  
Rule Of Law ◽  
Civil Society Organizations ◽  
The Rule Of Law ◽  
State Fragility ◽  
Family Types ◽  
Low Levels ◽  
Parsimonious Model ◽  
The One ◽  
High Level

Abstract Many years ago, Emmanuel Todd came up with a classification of family types and argued that the historically prevalent family types in a society have important consequences for its economic, political, and social development. Here, we evaluate Todd's most important predictions empirically. Relying on a parsimonious model with exogenous covariates, we find mixed results. On the one hand, authoritarian family types are, in stark contrast to Todd's predictions, associated with increased levels of the rule of law and innovation. On the other hand, and in line with Todd's expectations, communitarian family types are linked to racism, low levels of the rule of law, and late industrialization. Countries in which endogamy is frequently practiced also display an expectedly high level of state fragility and weak civil society organizations.

scholarly journals The S66 Non-Covalent Interactions Benchmark Reconsidered Using Explicitly Correlated Methods Near the Basis Set Limit

2018 ◽  
Vol 71 (4) ◽  
pp. 238 ◽  
Author(s):  
Manoj K. Kesharwani ◽  
Amir Karton ◽  
Nitai Sylvetsky ◽  
Jan M. L. Martin
Keyword(s):  
Computational Cost ◽  
The Other ◽  
Basis Set ◽  
Basis Sets ◽  
Explicitly Correlated ◽  
Non Covalent Interactions ◽  
Explicitly Correlated Methods ◽  
The One ◽  
High Level ◽  
Covalent Interactions

The S66 benchmark for non-covalent interactions has been re-evaluated using explicitly correlated methods with basis sets near the one-particle basis set limit. It is found that post-MP2 ‘high-level corrections’ are treated adequately well using a combination of CCSD(F12*) with (aug-)cc-pVTZ-F12 basis sets on the one hand, and (T) extrapolated from conventional CCSD(T)/heavy-aug-cc-pV{D,T}Z on the other hand. Implications for earlier benchmarks on the larger S66×8 problem set in particular, and for accurate calculations on non-covalent interactions in general, are discussed. At a slight cost in accuracy, (T) can be considerably accelerated by using sano-V{D,T}Z+ basis sets, whereas half-counterpoise CCSD(F12*)(T)/cc-pVDZ-F12 offers the best compromise between accuracy and computational cost.

scholarly journals Using Supermarket Loyalty Card Data to Provide Personalised Advice to Help Reduce Saturated Fat Intake among Patients with Hypercholesterolemia: A Qualitative Study of Participants’ Experiences

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1146
Author(s):  
Charlotte L. Lee ◽  
Paul N. Aveyard ◽  
Susan A. Jebb ◽  
Carmen Piernas
Keyword(s):  
Qualitative Study ◽  
Saturated Fat ◽  
Behavioural Intervention ◽  
Telephone Interviews ◽  
Food Purchases ◽  
Acceptable Method ◽  
The One ◽  
High Level ◽  
Brief Advice ◽  
Loyalty Card

Background: The ‘Primary Care SHOPping Intervention for Cardiovascular Disease Prevention’ (PCSHOP) trial tested the effectiveness and feasibility of a behavioural intervention to reduce saturated fat in food purchases. The intervention offered feedback from data collected through a supermarket loyalty card to supplement brief advice from a nurse. This qualitative study aimed to describe participants’ experiences of receiving this intervention. Methods: We conducted semi-structured, one-to-one, telephone interviews with participants from the PCSHOP trial. Interviews were audio-recorded and transcribed verbatim. We employed the one sheet of paper technique and a thematic analysis to develop high-level themes in NVivo software. Results: Twenty-four participants were interviewed (mean age: 63 years (SD 12)). They reported that the brief advice did not provide any new information but they welcomed the sense of accountability the nurse provided. The personalised shopping feedback and healthier swap suggestions provided novel information that challenged previously held beliefs about the saturated fat content of food purchases and encouraged some positive dietary changes. However, the taste preferences of the participant or other household members were a barrier to changing food shopping behaviours. Conclusion: Harnessing loyalty card data is a novel and acceptable method to offering personalised dietary feedback. Yet, issues on the suitability of the healthier swap suggestions limited the extent of dietary change. Trial registration: ISRCTN14279335. Registered 1 September 2017.

STUDY OF THE INFLUENCE OF THE LEVEL OF ANXIETY DEVELOPMENT ON THE ACADEMIC PERFORMANCE OF PRIMARY SCHOOL STUDENTS

Vestnik ◽  
2021 ◽  
pp. 155-160
Author(s):  
А.Е. Малибаева ◽  
Б.К. Кайрат ◽  
А.И. Нуфтиева ◽  
Л.Б. Умбетьярова ◽  
М.С. Кулбаева ◽  
...  
Keyword(s):  
Academic Performance ◽  
Learning Outcomes ◽  
Learning Process ◽  
Child Anxiety ◽  
Lower Class ◽  
The Other ◽  
Primary School Students ◽  
School Students ◽  
The One ◽  
High Level

В современных стрессовых и негативных внешних экологических условиях растет число неуверенных в себе, эмоционально неустойчивых тревожных детей. В работах А.И.Захаровой, Н.В.Имеладзе, Л.М. Прихожановой говорится, что когда человек постоянно волнуется - возникает паника. Согласно анализу исследований многих авторов, детская тревога, с одной стороны, имеет психодинкамическую природу, с другой-является результатом социализации. По мнению психологов, у учащихся наблюдается высокий уровень тревожности в процессе обучения. В результате изучения данной проблемы установлено, что уровень тревожности и успеваемость ребенка тесно взаимосвязаны. Процесс приобщения детей, пришедших в школу, к процессу обучения тесно связан с процессом паники . In the current stressful and negative external environmental conditions, the number of insecure, emotionally unstable children with anxiety is growing. In the works of A.I. Zakharova, N.V. Imeladze, L.M. Prikhozhan, it is said that when a person is constantly agitated, panic occurs. According to the analysis of the research of many authors, child anxiety, on the one hand, has a psychodynamic nature, and on the other-is the result of socialization. According to psychologists, there is a high level of anxiety in students ' learning process. As a result of the study of this problem, it was found that the level of anxiety and the child's academic performance are closely related. The process of adaptation of children to the learning process is closely related to the panic process. However, the level of anxiety in lower-class students affects the learning process and learning outcomes.

STUDI KRITIS JUAL BELI DEKORASI UANG MASKAWIN

Al-MAJAALIS ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 1-36
Author(s):  
Muhammad Arifin Badri
Keyword(s):  
The Other ◽  
Other Hand ◽  
Business Opportunities ◽  
The Law ◽  
The One ◽  
High Level

This study aims to examine the laws of dowry money decoration that are common in the community. The innovation and soul of art that is channeled through décor of dowry money is proven to produce beautiful and unique works, so as to attract the attention and interest of the wider community. However, because to produce beautiful and unique works, a high level of creativity is needed, so not everyone can do it. On the one hand, this phenomenon opens up quite good business opportunities, but on the other hand, it should be watched out, because in some conditions it contains the practice of buying and selling currencies with nominal differences. Through this study, I would like to uncover the law of buying and selling practices decorating dowry money and decorating services. As I also intend to present an applicative solution for the community so that they can still channel their artistic talents without violating Shari’ah law.

TO THE DYNAMICS OF THE NEED FOR STUDENTS' COMMUNICATION ACTIVITY COMPONENT AT THE PHARMACEUTICAL FACULTY OF VSMU

2021 ◽  
Vol 92 (2) ◽  
pp. 101-105
Author(s):  
A. L. Tserkovskiy ◽  
◽  
O. I. Gapova ◽  
E. A. Skorikova ◽  
S. A. Petrovich ◽  
...  
Keyword(s):  
Personal Growth ◽  
Professional Competence ◽  
Educational Process ◽  
Average Level ◽  
Psychological Service ◽  
Activity Component ◽  
The Social ◽  
Communication Activity ◽  
The One ◽  
High Level

The purpose of this research is to study the need for the students' communication activity component at the Pharmaceutical faculty of VSMU. Dual feature of the levels indicators dynamics in the need for communication is revealed. On the one hand, there is a tendency to reduce the average level in the need for communication and to increase its high level at the expense of girls. On the other hand, there is a fairly significant increase in the average level in the need for communication among young men against the background of an obvious predominance of the average level in the need for communication among the students of the entire sampling. The study allows us to state obvious influence of the informational educational environment at VSMU on the personal growth of students at the Pharmaceutical faculty, on the formation of their communicative competence as the most important component of the professional competence of future pharmacists. The results of the study can be used in the educational process of VSMU, in the activities of the social and pedagogical and psychological service, in the work of educators in academic groups and for tutors.

The Effect of Remote Work on the Successful Development of Engineering Companies

2021 ◽  
Vol 11 (4) ◽  
pp. 4345-4356
Author(s):  
Anna Evgenievna Gorokhova ◽  
Elman Said-Mokhmadovich Akhyadov ◽  
Andrey Nikolaevich Shishkin
Keyword(s):  
Corporate Culture ◽  
Working Hours ◽  
Remote Work ◽  
Transport Costs ◽  
Flexible Working Hours ◽  
Flexible Working ◽  
Insufficient Physical Activity ◽  
Effective Organization ◽  
The One ◽  
High Level

The purpose of the present study is to identify the main advantages and problems of remote work for both employers and employees, and possible ways to solve them. The article shows a significant number of studies dealt with non-standard forms of labor organization, clarifies the essence of remote work, and examines the main aspects for its effective organization. The main advantages and problems of remote work for employers and employees, as well as possible ways to solve them, are identified based on an expert survey involving 36 experts. According to the conducted study, it can be concluded that the acceleration of scientific and technological progress and adverse epidemiological conditions contribute to the spread of remote work worldwide. This phenomenon has two aspects. On the one hand, remote work, firstly, reduces the unemployment rate and improves the image of the company; secondly, offers flexible working hours; thirdly, protects/retains customers and saves time/transport costs. On the other hand, remote work is associated with the difficulty in maintaining efficiency and teamwork at a high level; secondly, it restricts communication, makes it impossible to perform certain tasks at home; and thirdly, remote work leads to insufficient physical activity, causes difficulties with integration into the corporate culture, etc.

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