scholarly journals Decentralized Phase Shedding with Low Power Mode for Multiphase Converter

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6748
Author(s):  
Marc Cousineau ◽  
Martin Monroy ◽  
William Lorenzi Pol ◽  
Loic Hureau ◽  
Guillaume Aulagnier ◽  
...  
Keyword(s):  
Power Efficiency ◽  
Single Point ◽  
Chain Structure ◽  
Optimal Number ◽  
Load Current ◽  
Control Approach ◽  
Start Up ◽  
Tracking Ability ◽  
Local Decision ◽  
Local Controller

With a multiphase converter, the phase-shedding function dedicated to maximizing the power efficiency, in a manner that is dependent on the load current, is always provided by a centralized controller that induces a Single Point of Failure (SPOF). The objective of this study is to obtain a decentralized control approach to implement this function by removing any SPOF. The method consists of using identical local controllers, each associated with a converter phase, that communicate with each other in a daisy-chain structure. Instead of measuring the global output current to determine the optimal number of active phases required, each local controller measures its own leg current and takes a local decision based on threshold crossing management and inter-controller communications. Functional simulations are carried out on a 5-leg 12 V/1.2 V 60 W multiphase converter supplying a modern microcontroller. They demonstrate that the number of active phases is well adjusted, in a dynamic manner, depending on the load current level. Specific events such as load current inrush or the start-up sequence are analyzed to guarantee optimal transient responses. A maximum power efficiency tracking ability is also demonstrated. Finally, it is shown that this control strategy allows phase shedding to be implemented using as many phases as desired, in a modular manner, thereby avoiding any centralized processing.

scholarly journals IoT-CCAC: a blockchain-based consortium capability access control approach for IoT

2021 ◽  
Vol 7 ◽  
pp. e455
Author(s):  
Mohammed Amine Bouras ◽  
Boming Xia ◽  
Adnan Omer Abuassba ◽  
Huansheng Ning ◽  
Qinghua Lu
Keyword(s):  
Access Control ◽  
Single Point ◽  
Poor Performance ◽  
Sharing Economy ◽  
Privacy And Security ◽  
Control Approach ◽  
Blockchain Technology ◽  
Control Schemes ◽  
Common Goals ◽  
Intrinsic Feature

Access control is a critical aspect for improving the privacy and security of IoT systems. A consortium is a public or private association or a group of two or more institutes, businesses, and companies that collaborate to achieve common goals or form a resource pool to enable the sharing economy aspect. However, most access control methods are based on centralized solutions, which may lead to problems like data leakage and single-point failure. Blockchain technology has its intrinsic feature of distribution, which can be used to tackle the centralized problem of traditional access control schemes. Nevertheless, blockchain itself comes with certain limitations like the lack of scalability and poor performance. To bridge the gap of these problems, here we present a decentralized capability-based access control architecture designed for IoT consortium networks named IoT-CCAC. A blockchain-based database is utilized in our solution for better performance since it exhibits favorable features of both blockchain and conventional databases. The performance of IoT-CCAC is evaluated to demonstrate the superiority of our proposed architecture. IoT-CCAC is a secure, salable, effective solution that meets the enterprise and business’s needs and adaptable for different IoT interoperability scenarios.

scholarly journals Field Test and Numerical Simulation of Dynamic Compaction of High Embankment Filled with Soil-Rock

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Lu Zhang ◽  
Guangqing Yang ◽  
Dongliang Zhang ◽  
Zhijie Wang ◽  
Jing Jin
Keyword(s):  
Stress Field ◽  
Plastic Zone ◽  
Field Test ◽  
Displacement Field ◽  
Single Point ◽  
Energy Levels ◽  
Field Tests ◽  
Optimal Number ◽  
Dynamic Compaction ◽  
Granular Soil

In view of the high filling height and large amount of soil and rock in the high-filled embankment, the variation law of the displacement field, stress field, and plastic zone of embankment body reinforced by dynamic compaction with different energy levels and the optimal compaction energy were analyzed by means of numerical simulations and field tests. Taking the embankment section of the Ping-Zan highway as an example, the construction scheme of dynamic compaction was designed, and the optimum tamping times and effective dynamic compaction depth of the embankment filled with soil-rock were obtained through the field test. The study showed that the displacement field and the stress field are redistributed after applying single-point compaction, and the volume of the shear plastic zone increases. The optimal number of slams for high-filled granular soil is 7 times, and the effective depth of dynamic compaction is 4.5 m. The result corresponds with that by the field test, which indicates that dynamic compaction is reasonable and has a significant effect on the high embankment filled with granular soil.

scholarly journals A Nano-Power 0.5 V Event-Driven Digital-LDO with Fast Start-Up Burst Oscillator for SoC-IoT

2020 ◽  
Vol 10 (4) ◽  
pp. 41
Author(s):  
Christos Konstantopoulos ◽  
Thomas Ussmueller
Keyword(s):  
Power Efficiency ◽  
High Gain ◽  
Ring Oscillator ◽  
Cmos Process ◽  
Ultra Low Power ◽  
Clock Generation ◽  
Start Up ◽  
Fast Start ◽  
Main Regulator ◽  
Gain Stage

Towards the integration of Digital-LDO regulators in the ultra-low-power System-On-Chip Internet-of-Things architecture, the D-LDO architecture should constitute the main regulator for powering digital and mixed-signal loads including the SoC system clock. Such an implementation requires an in-regulator clock generation unit that provides an autonomous D-LDO design. In contrast to contemporary D-LDO designs that employ ring-oscillator architecture which start-up time is dependent on the oscillating frequency, this work presents a design with nano-power consumption, fabricated with an active area of 0.035 mm2 at a 55-nm Global Foundries CMOS process that introduces a fast start-up burst oscillator based on a high-gain stage with wake-up time independent of D-LDO frequency. In combination with linear search coarse regulation and asynchronous fine regulation, it succeeds 558 nA minimum quiescent current with CL 75 pF, maximum current efficiency of 99.2% and 1.16x power efficiency improvement compared to analog counterpart oriented to SoC-IoT loads.

APPLICATION OF NUCLEONIC INSTRUMENTS IN SEPARATOR PROFILING: KUITO FPSO CASE STUDY

2006 ◽  
Vol 46 (1) ◽  
pp. 405
Author(s):  
B. Beinart
Keyword(s):  
Deep Water ◽  
Oil And Gas ◽  
Produced Water ◽  
Single Point ◽  
Oil Production ◽  
Fluid Interface ◽  
Start Up ◽  
Fluid Levels ◽  
Separation Problems

The Kuito field lies in the offshore Cabinda Province, Angola. Kuito was Angola’s first deep-water oil and came on stream in December 1999. Kuito oil is produced via an FPSO. Kuito oil ranges 18–22 API. The FPSO has threephase, horizontal, gravity separation vessels that are used to separate oil and gas from unwanted produced water and solids prior to transportation. The production separators were designed with traditional, single point transmitters for measurement of the fluid interface and overall fluid levels. These were capacitance type instruments mounted inside the vessels in stilling wells.Following production start-up, separation problems began to emerge; these were manifested in numerous process upsets and shutdowns. Kuito oil can form emulsions quickly, and calcium naphthenate is produced at higher temperatures. If allowed to cool, it solidifies. The point instrumentation was unable to detect these emulsion and naphthenate layers resulting in the instrumentation becoming fouled and ceasing to function. The separators were operated ‘blind’, using tri-cocks located on the side of the vessel, and as the instrumentation was installed in stilling wells inside the vessel, it was impossible to maintain them without shutting down and depressurising the vessels. This paper describes how nucleonic profiling instruments were retrofitted to the vessels and shows how their operation was able to identify the different layers within the separators. This enabled the time of oil production to be increased and allowed the pro-active use of effect chemicals such as emulsion breakers and defoamers to be applied before the plant became unstable.

scholarly journals Diseases and Geographic Variation: Are we missing the whole picture?

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Gareth John
Keyword(s):  
Large Scale ◽  
Single Point ◽  
Control Group ◽  
Epidemiological Analysis ◽  
Control Approach ◽  
Time Period ◽  
Risk Approach ◽  
History Of ◽  
Health And Disease ◽  
And Gender

ABSTRACT BackgroundEpidemiology is the study and analysis of the patterns, causes, and effects of health and disease conditions in defined populations. However, where an epidemiological analysis relies solely on data from large-scale anonymous administrative data sources, the available geographic information for the individuals concerned relates in general to just one single point in time; for example the places of residence of individual on the day that they were registered with a particular disease, or their places of residence on the day that they were admitted to hospital. This information may not be sufficient however, especially when considering diseases where there may be a long period of time between an exposure to a particular hazard and the subsequent onset of disease. MethodA solution to this problem possibly lies within administrative sources of data such as the Welsh Demographic Service (WDS), which is accessible to NHS Wales analysts and users of the SAIL databank in a pseudonymised format. The WDS contains the details of all Welsh residents who have been registered with a GP Practice since 1992, including a full history of changes to their addresses and GP practices. This data can be used to easily ascertain an individual’s address at any point in time, for example on a particular census date, or within a time period that is relative to a particular event, e.g. 10 years prior to disease registration. However, this research will look at how to incorporate all of an individual’s available address information into an epidemiological analysis. ResultsTwo main approaches will be demonstrated; the first using a “Person Years at Risk” approach which attempts to apportion numerator and denominator according to the number of previous residences, and the second using a Case Control approach, comparing the geographic spread of addresses in the diseased group of patients versus the non-diseased (control) group, with age and gender matched controls also drawn from the WDS.

scholarly journals Mathematical Modeling and Performance Evaluation of Switched-Capacitor-Based Battery Equalization Systems

Electronics ◽  
2021 ◽  
Vol 10 (21) ◽  
pp. 2629
Author(s):  
Kun-Che Ho ◽  
Yi-Hua Liu ◽  
Song-Pei Ye ◽  
Guan-Jhu Chen ◽  
Yu-Shan Cheng
Keyword(s):  
Power Efficiency ◽  
Low Cost ◽  
Storage System ◽  
Chain Structure ◽  
Practical Implementation ◽  
Switched Capacitor ◽  
Matlab Simulation ◽  
Renewable Energy Systems ◽  
Charge Imbalance ◽  
And Performance

The battery storage system (BSS) is one of the key components in many modern power applications, such as in renewable energy systems and electric vehicles. However, charge imbalance among batteries is very common in BSSs, which may impair the power efficiency, reliability, and safety. Hence, various battery equalization methods have been proposed in the literature. Among these techniques, switched-capacitor (SC)-based battery equalizers (BEs) have attracted much attention due to their low cost, small size, and controllability. In this paper, seven types of SC-based BEs are studied, including conventional, double-tiered, modularized, chain structure types I and II, series-parallel, and single SC-based BEs. Mathematical models that describe the charge–discharge behaviors are first derived. Next, a statistical analysis based on MATLAB simulation is carried out to compare the performance of these seven BEs. Finally, a summary of the circuit design complexity, balancing speed, and practical implementation options for these seven topologies is provided.

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