scholarly journals Quantifying the Environmental Design Trades for a State-of-the-Art Turbofan Engine

Aerospace ◽  
2020 ◽  
Vol 7 (10) ◽  
pp. 148 ◽  
Author(s):  
Evangelia Maria Thoma ◽  
Tomas Grönstedt ◽  
Xin Zhao
Keyword(s):  
State Of The Art ◽  
Fuel Efficiency ◽  
Aviation Industry ◽  
Optimal Point ◽  
Turbofan Engine ◽  
System A ◽  
Multidisciplinary Modeling ◽  
Engine Nacelle ◽  
Modest Effect ◽  
Made In

Aircraft and engine technology have continuously evolved since their introduction and significant improvement has been made in fuel efficiency, emissions, and noise reduction. One of the major issues that the aviation industry is facing today is pollution around the airports, which has an effect both on human health and on the climate. Although noise emissions do not have a direct impact on climate, variations in departure and arrival procedures influence both CO2 and non-CO2 emissions. In addition, design choices made to curb noise might increase CO2 and vice versa. Thus, multidisciplinary modeling is required for the assessment of these interdependencies for new aircraft and flight procedures. A particular aspect that has received little attention is the quantification of the extent to which early design choices influence the trades of CO2, NOx, and noise. In this study, a single aisle thrust class turbofan engine is optimized for minimum installed SFC (Specific Fuel Consumption). The installed SFC metric includes the effect of engine nacelle drag and engine weight. Close to optimal cycles are then studied to establish how variation in engine cycle parameters trade with noise certification and LTO (Landing and Take-Off) emissions. It is demonstrated that around the optimum a relatively large variation in cycle parameters is allowed with only a modest effect on the installed SFC metric. This freedom in choosing cycle parameters allows the designer to trade noise and emissions. Around the optimal point of a state-of-the-art single aisle thrust class propulsion system, a 1.7 dB reduction in cumulative noise and a 12% reduction in EINOx could be accomplished with a 0.5% penalty in installed SFC.

Biological Production of (S)-acetoin: A State-of-the-Art Review

2019 ◽  
Vol 19 (25) ◽  
pp. 2348-2356 ◽  
Author(s):  
Neng-Zhong Xie ◽  
Jian-Xiu Li ◽  
Ri-Bo Huang
Keyword(s):  
Side Effects ◽  
Chemical Synthesis ◽  
State Of The Art ◽  
Optically Active ◽  
Considerable Progress ◽  
Future Prospects ◽  
Chiral Compound ◽  
Biological Production ◽  
Acetoin Production ◽  
Made In

Acetoin is an important four-carbon compound that has many applications in foods, chemical synthesis, cosmetics, cigarettes, soaps, and detergents. Its stereoisomer (S)-acetoin, a high-value chiral compound, can also be used to synthesize optically active drugs, which could enhance targeting properties and reduce side effects. Recently, considerable progress has been made in the development of biotechnological routes for (S)-acetoin production. In this review, various strategies for biological (S)- acetoin production are summarized, and their constraints and possible solutions are described. Furthermore, future prospects of biological production of (S)-acetoin are discussed.

scholarly journals Study and Analysis of Interference Signals of the LTE System of the GNSS Receiver

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4901
Author(s):  
Lucjan Setlak ◽  
Rafał Kowalik
Keyword(s):  
End User ◽  
Current Time ◽  
Gnss Receiver ◽  
System A ◽  
Telecommunication Systems ◽  
Depth Analysis ◽  
Gnss Receivers ◽  
Interference Signals ◽  
The Subject ◽  
Made In

Sometimes, it is impossible to conduct tests with the use of the GNSS system, or the obtained results of the measurements made differ significantly from the predicted accuracy. The most common cause of the problems (external factors, faulty results) are interference disturbances from other radio telecommunication systems. The subject of this paper is to conduct research, the essence of which is an in-depth analysis in the field of elimination of LTE interference signals of the GNSS receiver, that is based on the developed effective methods on counteracting the phenomenon of interference signals coming from this system and transmitted on the same frequency. Interference signals are signals transmitted in the GNSS operating band, and unwanted signals may cause incorrect processing of the information provided to the end-user about his position, speed, and current time. This article presents methods of identifying and detecting interference signals, with particular emphasis on methods based on spatial processing of signals transmitted by the LTE system. A comparative analysis of the methods of detecting an unwanted signal was made in terms of their effectiveness and complexity of their implementation. Moreover, the concept of a new comprehensive anti-interference solution was proposed. It includes, among others, information on the various stages of GNSS signal processing in the proposed system, in relation to the algorithms used in traditional GNSS receivers. The final part of the article presents the obtained research results and the resulting significant observations and practical conclusions.

scholarly journals Analysis of the Practical Implementation of Flicker Measurement Coprocessor for AMI Meters

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1589
Author(s):  
Krzysztof Kołek ◽  
Andrzej Firlit ◽  
Krzysztof Piątek ◽  
Krzysztof Chmielowiec
Keyword(s):  
Code Generation ◽  
State Of The Art ◽  
Power Grids ◽  
Practical Implementation ◽  
System A ◽  
Measuring Devices ◽  
Point Representation ◽  
Measurement Algorithm ◽  
On Chip ◽  
Vhdl Code

Monitoring power quality (PQ) indicators is an important part of modern power grids’ maintenance. Among different PQ indicators, flicker severity coefficients Pst and Plt are measures of voltage fluctuations. In state-of-the-art PQ measuring devices, the flicker measurement channel is usually implemented as a dedicated processor subsystem. Implementation of the IEC 61000-4-15 compliant flicker measurement algorithm requires a significant amount of computational power. In typical PQ analysers, the flicker measurement is usually implemented as a part of the meter’s algorithm performed by the main processor. This paper considers the implementation of the flicker measurement as an FPGA module to offload the processor subsystem or operate as an IP core in FPGA-based system-on-chip units. The measurement algorithm is developed and validated as a Simulink diagram, which is then converted to a fixed-point representation. Parts of the diagram are applied for automatic VHDL code generation, and the classifier block is implemented as a local soft-processor system. A simple eight-bit processor operates within the flicker measurement coprocessor and performs statistical operations. Finally, an IP module is created that can be considered as a flicker coprocessor module. When using the coprocessor, the main processor’s only role is to trigger the coprocessor and read the results, while the coprocessor independently calculates the flicker coefficients.

Developments in Rechargeable Mno2Electrodes for Lithium Batteries

1988 ◽  
Vol 135 ◽  
Author(s):  
Michael M Thackeray
Keyword(s):  
Lithium Batteries ◽  
Lithium Battery ◽  
Electrode Materials ◽  
State Of The Art ◽  
Structural Features ◽  
Rechargeable Batteries ◽  
Current State ◽  
Alternative Systems ◽  
Battery Technology ◽  
Made In

AbstractConsiderable efforts are in progress to develop rechargeable batteries as alternative systems to the nickel-cadmium battery. In this regard, several advances have been made in ambient-temperature lithium battery technology, and specifically in the engineering of rechargeable lithium/manganese dioxide cells. This paper reviews the current state of the art in rechargeable Li/MnO2battery technology; particular attention is paid to the structural features of various MnO2electrode materials which influence their electrochemical and cycling behaviour in lithium cells.

"A FESTIVAL OF BRIGANDS": IN SEARCH OF DEMOCRACY AND POLITICAL LEGITIMACY IN MALI

2020 ◽  
Vol 35 (2) ◽  
Author(s):  
Bruce Whitehouse
Keyword(s):  
Political Legitimacy ◽  
Warning Signs ◽  
Democratic Transitions ◽  
Weak State ◽  
Coup D'etat ◽  
State Institutions ◽  
System A ◽  
The Government ◽  
Systemic Corruption ◽  
Made In

Mali's coup d'état in March 2012 and the subsequent occupation of northern Mali by Islamist and separatist rebels took many observers by surprise. How could an erstwhile model of peaceful democratic transition collapse so swiftly? Why did so few ordinary Malians stand up in defence of their 20-year-old democracy? Combining accounts from Malian and foreign journalists with observations made in Bamako leading up to and during the dramatic events of early 2012, this article assesses the failures of Mali's pre-coup political system. A combination of the tenuous rule of law, weak state institutions, and perceptions of systemic corruption deeply eroded Malians' faith in their democracy. The junta that ousted Mali's elected president in March 2012, despite its international isolation, skillfully manipulated public frustrations with the government as well as local symbols and discourses pertaining to heroic leaders to gain support and legitimacy at home. The crisis in Mali was preceded by certain warning signs, some of which might be applied to gauge the health of democratic transitions elsewhere in Africa.

State of the Art — 1973

1973 ◽  
Vol 18 (3) ◽  
pp. 175-183 ◽  
Author(s):  
Nathan B. Epstein ◽  
Duane S. Bishop
Keyword(s):  
State Of The Art ◽  
Therapeutic Process ◽  
Scientific Discipline ◽  
Therapeutic Approaches ◽  
Training And Education ◽  
Rigorous Approach ◽  
The Family ◽  
Process And Outcome ◽  
Scientific Approach ◽  
Made In

In summary, it can be said that progress is being made in the field, but slowly. The ‘art’ is vigorous, vital and exciting. The ranks of family therapists are swelling and they are coming from backgrounds of different theoretical persuasions and with varying degrees of sophistication in their training and education. This mélange does lead to excitement and turbulence but often detracts from the necessary rigour that a scientific discipline must develop in order to reach maturity. Systems theory allows for easy conceptualization of one another's behaviour in the system, and permits a much clearer understanding of the therapeutic process based upon it, in contrast to therapeutic approaches based on other models. The authors found negotiation to be therapeutically effective when made explicit. In addition they place the focus on the ‘here and now’ and encourage the increased labeling by family members of interactions (affective and behavioural) and their effects (affective and behavioural), according to the Family Categories Schema previously referred to. Efforts are directed especially towards dealing with the current resistances to problem solutions. Epstein et al. have reported on an ongoing program of research which attempts to examine the process and outcome of family therapy (7,10,21,22,25,26). What is needed now is a more rigorous approach to research and the development of a necessary theoretical base in order that a more systematic and scientific approach can be developed for treating families.

scholarly journals Social and Solidarity Economy Web Information Systems

2014 ◽  
Vol 12 (1) ◽  
pp. 35-52 ◽  
Author(s):  
Mariana Curado Malta ◽  
Ana Alice Baptista ◽  
Cristina Parente
Keyword(s):  
Information Systems ◽  
State Of The Art ◽  
Bibliographic Databases ◽  
Sources Of Information ◽  
Solidarity Economy ◽  
Web Based ◽  
Web Information ◽  
The Social ◽  
Application Profile ◽  
Made In

This paper presents the state of the art on interoperability developments for the social and solidarity economy (SSE) community web based information systems (WIS); it also presents a framework of interoperability for the SSE' WIS and the developments made in a research-in-progress PhD project in the last 3 years. A search on the bibliographic databases showed that so far there are no papers on interoperability initiatives on the SSE, so it was necessary to have other sources of information: a preliminary analysis of the WIS that support SSE activities; and interviews with the representatives of some of the world's most important SSE organisations. The study showed that the WIS are still not interoperable yet. In order to become interoperable a group of the SSE community has been developing a Dublin Corre Application Profile to be used by the SSE community as reference and binding to describe their resources. This paper also describes this on-going process.

scholarly journals SetRank: A Setwise Bayesian Approach for Collaborative Ranking from Implicit Feedback

2020 ◽  
Vol 34 (04) ◽  
pp. 6127-6136
Author(s):  
Chao Wang ◽  
Hengshu Zhu ◽  
Chen Zhu ◽  
Chuan Qin ◽  
Hui Xiong
Keyword(s):  
Bayesian Approach ◽  
Posterior Probability ◽  
State Of The Art ◽  
User Preferences ◽  
Implicit Feedback ◽  
Pairwise Preference ◽  
Entire List ◽  
Collaborative Ranking ◽  
Real World Datasets ◽  
Made In

The recent development of online recommender systems has a focus on collaborative ranking from implicit feedback, such as user clicks and purchases. Different from explicit ratings, which reflect graded user preferences, the implicit feedback only generates positive and unobserved labels. While considerable efforts have been made in this direction, the well-known pairwise and listwise approaches have still been limited by various challenges. Specifically, for the pairwise approaches, the assumption of independent pairwise preference is not always held in practice. Also, the listwise approaches cannot efficiently accommodate “ties” due to the precondition of the entire list permutation. To this end, in this paper, we propose a novel setwise Bayesian approach for collaborative ranking, namely SetRank, to inherently accommodate the characteristics of implicit feedback in recommender system. Specifically, SetRank aims at maximizing the posterior probability of novel setwise preference comparisons and can be implemented with matrix factorization and neural networks. Meanwhile, we also present the theoretical analysis of SetRank to show that the bound of excess risk can be proportional to √M/N, where M and N are the numbers of items and users, respectively. Finally, extensive experiments on four real-world datasets clearly validate the superiority of SetRank compared with various state-of-the-art baselines.

scholarly journals The Linkage of the Board of Directors and the Status of Aviation Industry Licensing Law

2017 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
LESTARI NINGRUM
Keyword(s):  
Legal Status ◽  
Limited Liability ◽  
Third Party ◽  
Aviation Industry ◽  
Limited Liability Company ◽  
Basic Capital ◽  
The Status ◽  
Business Entities ◽  
Capital Intensive ◽  
Made In

Aviation business is a capital intensive and high risk in terms of safety. Legislation in force in Indonesia requires enterprises should cost in the form of a limited liability company that is obliged to deposit the basic capital of 500 billion rupiah. The capital cannot be made in working capital which is useful for the collateral to a third party. The regulations for a limited liability company are to be established by at least 2 people. The purpose of this research is to analyze the linkage of the board directors and the status of aviation industry licensing law. The position of the legal status of business entities where shareholder is only one person is to be studied in this descriptive study. The result shows that the airlines company should provide the capital risk and high insurance of the third party. UUPT also has given the authority of the shareholders (who owns 20 % of the share) to be decision makers in the company. However, without independent surveillance, it is possible that the shareholders do some mistakes in making decisions. Some mistakes are related to the policy, the using of authorized capital, and others. Aviation business is a capital intensive and high risk in terms of safety. Legislation in force in Indonesia requires enterprises should cost in the form of a limited liability company that is obliged to deposit the basic capital of 500 billion rupiah. The capital cannot be made in working capital which is useful for the collateral to a third party. The regulations for a limited liability company are to be established by at least 2 people. The position of the legal status of business entities where shareholder is only one person is to be studied in this descriptive study.

scholarly journals Predictive modelling of turbofan engine components condition using machine and deep learning methods

2021 ◽  
Vol 23 (2) ◽  
pp. 359-370
Author(s):  
Michał Matuszczak ◽  
Mateusz Żbikowski ◽  
Andrzej Teodorczyk
Keyword(s):  
Machine Learning ◽  
Deep Learning ◽  
Predictive Modelling ◽  
Continuous Variable ◽  
Environmental Data ◽  
Bayesian Optimization ◽  
Aviation Industry ◽  
Learning Models ◽  
Turbofan Engine ◽  
Machine Learning Models

The article proposes an approach based on deep and machine learning models to predict a component failure as an enhancement of condition based maintenance scheme of a turbofan engine and reviews currently used prognostics approaches in the aviation industry. Component degradation scale representing its life consumption is proposed and such collected condition data are combined with engines sensors and environmental data. With use of data manipulation techniques, a framework for models training is created and models' hyperparameters obtained through Bayesian optimization. Models predict the continuous variable representing condition based on the input. Best performed model is identified by detemining its score on the holdout set. Deep learning models achieved 0.71 MSE score (ensemble meta-model of neural networks) and outperformed significantly machine learning models with their best score at 1.75. The deep learning models shown their feasibility to predict the component condition within less than 1 unit of the error in the rank scale.

Sign in / Sign up

Export Citation Format

Share Document