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control complexity in Bucklin and fallback voting: A theoretical analysis

JOURNAL OF COMPUTER AND SYSTEM SCIENCES 2015年第4期81卷 632-660页

作者： Erdelyi, Gabor Fellows, Michael R. Rothe, Joerg Schend, Lena Univ Siegen Sch Econ Disciplines D-57076 Siegen Germany Charles Darwin Univ Parameterized Complex Res Unit Darwin NT 0909 Australia Univ Dusseldorf Inst Informat D-40225 Dusseldorf Germany

Electoral control models ways of changing the outcome of an election via such actions as adding, deleting, or partitioning either candidates or voters. To protect elections from such control attempts, computational complexity has been used to establish so-called resistance results. We show that fallback voting, an election system proposed by Brams and Sanver [12] to combine Bucklin with approval voting, displays the broadest control resistance currently known to hold among natural election systems with a polynomial-time winner problem. We also study the control complexity of Bucklin voting and show that it performs almost as well as fallback voting in terms of control resistance. Furthermore, we investigate the parameterized control complexity of Bucklin and fallback voting, according to several parameters that are often likely to be small for typical instances. In a companion paper [28], we challenge our worst-case complexity results from an experimental point of view. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Computational social choice control complexity Bucklin voting Fallback voting Parameterized complexity Election systems

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control complexity in Bucklin and fallback voting: An experimental analysis

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JOURNAL OF COMPUTER AND SYSTEM SCIENCES 2015年第4期81卷 661-670页

control in elections models situations in which an external actor tries to change the outcome of an election by restructuring the election itself. The corresponding decision problems have been shown NP-hard for a variety of voting systems. In particular, in our companion paper [16], we have shown that fallback and Bucklin voting are resistant (in terms of NP-hardness) to almost all of the common types of control. While NP-hardness results for manipulation (another way of tampering with the outcomes of elections) have been challenged experimentally (see, e.g., the work of Walsh [38,37]), such an experimental approach is sorely missing for control. We for the first time tackle NP-hard control problems in an experimental setting. Our experiments allow a more fine-grained analysis and comparison-across various control scenarios, vote distribution models, and voting systems-than merely stating NP-hardness for all these control problems. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Computational social choice control complexity Bucklin voting Fallback voting Experimental analysis Election systems

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Influence of Monitoring Method and control complexity on Operator Performance in Manually controlled Spacecraft Rendezvous and Docking

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Tsinghua Science and Technology 2008年第5期13卷 619-624页

作者：张宜静徐永忠李志忠李洁吴甦 Department of Industrial Engineering Tsinghua University China Astronaut Research and Training Center

This study focuses on the influence of the monitoring method and control complexity on the operator performance in manually controlled spacecraft rendezvous and docking （RVD）. Two one-factor experiments were designed on a simulated RVD system. One examined the video guidance and periscope monitoring methods, and the other examined three control complexity levels using one-axis RVD control, two-axis RVD control, and three-axis RVD control. Eighteen male volunteers aged 22-35 participated in the experiments. The results show that the RVD operating time increases with control complexity. Based on the operators＇ findings, the two-axis control is the easiest. The monitoring method has no significant influence on failure rate with the low complexity using one-axis RVD control.

关键词： spacecraft rendezvous and docking (RVD) monitoring method control complexity

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Influence of control modes and complexity on performance of manual-control spacecraft rendezvous and docking

Influence of control modes and complexity on performance of ...

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IEEE International Conference on Industrial Engineering and Engineering Management

作者： Zhang, Y. J. Xu, Y. Z. Lie, J. Li, Z. Z. Wu, S. Tsinghua Univ Dept Ind Engn Beijing 100084 Peoples R China China Astronaut Res & Training Ctr Beijing 100094 Peoples R China

ISBN: (纸本)9781424415281

Spacecraft rendezvous and docking (RVD) is one of the major tasks in space flight mission. This study focused on the influence of control modes and complexity on the Chinese operator performance in manual-controlled RVD. A simulated RVD system was developed. 15 male subjects aged 23-40 participated in the experiment. Examined in the experiment were two control modes (mode A - engine control and mode B direct control) and three task complexity levels ( level 1 - one axis RVD control, level 2 - two axes RVD control, and level 3 - three axes RVD control). Conclusions from the statistical analysis on the experiment data include: control mode A required longer operation time than mode B did;the RVD operation time increased with the increase of task complexity;under task complexity level 2, operators felt much better to finish the RVD control tasks;and subjects preferred control mode B which was conformable to their operate experience. These conclusions can be useful to the spacecraft design and astronauts training.

关键词： control complexity control mode manual control rendezvous and docking

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complexity of control by partitioning veto elections and of control by adding candidates to plurality elections

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ANNALS OF MATHEMATICS AND ARTIFICIAL INTELLIGENCE 2018年第4期82卷 219-244页

作者： Maushagen, Cynthia Rothe, Joerg Heinrich Heine Univ Dusseldorf Inst Informat Univ Str 1 Dusseldorf Germany

control by partition refers to situations where an election chair seeks to influence the outcome of an election by partitioning either the candidates or the voters into two groups, thus creating two first-round subelections that determine who will take part in a final round. The model of partition-of-voters control attacks is remotely related to "gerrymandering" (maliciously resizing election districts). While the complexity of control by partition has been studied thoroughly for many voting systems, there are no such results known for the important veto voting system. We settle the complexity of control by partition for veto in a broad variety of models. In addition, by giving a counterexample we observe that a reduction from the literature (Chen et al. 2015) showing the parameterized complexity of control by adding candidates to plurality elections, parameterized by the number of voters, is technically flawed, and we show how this reduction can be adapted to make it correct.

关键词： Computational social choice Voting Veto election control complexity

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Coupled inductor-based single-stage high gain DC-AC buck-boost inverter

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IET POWER ELECTRONICS 2016年第8期9卷 1590-1599页

作者： Sreekanth, T. Lakshminarasamma, N. Mishra, Mahesh Kumar Indian Inst Technol Madras Dept Elect Engn Madras Tamil Nadu India

Two stage conversion systems (TSCSs) normally use either boost converter or high gain dc-dc converter along with dc-ac inverter in order to transfer power from low input voltage dc source to high voltage ac load. When these TSCSs operate at extremely low input voltages, the boost converter has to operate at extremely high duty ratios. This in turn results in more losses and reverse recovery problems. Usage of high gain dc-dc converter results in more number of components, increase in control complexity and decrease in reliability. Single-stage conversion systems (SSCSs) are formed by merging both dc-dc and dc-ac conversion processes. These SSCSs have advantages like low loss, more compactness and less reverse recovery problems. In this study, a high gain coupled inductor-based single-phase SSCS is presented. This SSCS topology has many desirable features such as high gain, less switching losses, free from leakage inductance adverse effects and compact. Principle of operation, steady-state analysis and design of the proposed topology are described in detail. MATLAB simulation results of the proposed topology and experimental results using DSP28335-based experimental setup are presented to validate the proposed scheme.

关键词： invertors coupled inductor-based single-stage high gain DC-AC buck-boost inverter TSCSs two stage conversion systems boost converter high gain DC-DC converter low input voltage dc source high voltage ac load duty ratios reverse recovery problems control complexity single-stage conversion systems dc-ac conversion process high gain coupled inductor-based single-phase SSCS steady-state analysis Matlab simulation DSP28335-based experimental setup

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Hierarchical voltage balancing method for MMC based on DCSM

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IET POWER ELECTRONICS 2022年第14期15卷 1583-1595页

作者： Li, Dongye Ji, Zhendong Zhao, Jianfeng Sun, Yichao Wang, Shuzheng Ni, Xijun Nanjing Inst Technol Sch Elect Power Engn 1 Hongjing Avenu Nanjing 211167 Peoples R China Nanjing Univ Sci & Technol Sch Automat Nanjing Peoples R China Southeast Univ Sch Elect Engn Nanjing Peoples R China Nanjing Normal Univ Sch Elect & Automat Engn Nanjing Peoples R China

This paper presents a hierarchical voltage balance control method for a hybrid modular multi-level converter based on half-bridge submodule and dual-capacitor submodule. This voltage balancing method reduces the control complexity of the existing voltage balancing method of the central controller but does not significantly increase the control complexity of the submodule controller. In dual-capacitor submodule, only some logic operations are added. Furthermore, the proposed method reduces the hardware requirements and communication data between the submodule and central controllers. The reduced hardware requirements refer to the hardware circuits used to implement communication functions. The proposed method is also applicable to multi-level converter, which only includes half-bridge submodules, but requires two adjacent half-bridge submodules to use the same submodule controller. Simulation and experimental results validate the feasibility and effectiveness of the proposed hierarchical voltage balance control.

关键词： control complexity reduced hardware requirements hierarchical voltage balance control method submodule controllers central controllers submodule controller voltage-source convertors HVDC power convertors hybrid modular multilevel converter half-bridge submodule dual-capacitor submodule voltage control central controller existing voltage balancing method hierarchical voltage balancing method adjacent half-bridge submodules power capacitors

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Performance optimisation of the grid-connected flyback inverter under improved hybrid conduction mode

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IET RENEWABLE POWER GENERATION 2020年第13期14卷 2437-2446页

作者： Mohammadi, Saleh Izadfar, Hamid Reza Eskandarian, Naser Semnan Univ Fac Elect & Comp Engn Semnan Iran

In the unfolding-type interleaved two-switch flyback inverter (ILTFI) operating in discontinuous conduction mode (DCM), the hybrid control strategy combining the one-phase DCM and the two-phase DCM has a significant impact on improving the efficiency under all load conditions. In the situation where the marginal power of this control strategy is increased, the converter may enter CCM. Consequently, the converter cannot track the reference current and the output current quality is notably decreased. To tackle this issue, a novel hybrid control method is proposed which varies the switching frequency based on the output power. The proposed approach is immune to the loss analysis and power losses of the components. Hence, it is independent of components selection and their characteristics. In this case, the smooth transition between the one-phase and the two-phase operation modes is guaranteed without affecting the output power quality and the stability of the converter in DCM. The control complexity of the proposed scheme is low and the converter can be easily controlled in DCM. The performance of the flyback microinverter with the proposed hybrid control scheme is verified by the simulation and the experimental results together with the loss analysis.

关键词： electric current control invertors power grids photovoltaic power systems switching convertors power supply quality performance optimisation grid-connected flyback inverter improved hybrid conduction mode discontinuous conduction mode hybrid control strategy one-phase DCM two-phase DCM load conditions marginal power continuous conduction mode reference current output current quality novel hybrid control method switching frequency loss analysis power losses components selection two-phase operation modes output power quality wide load ranges low-output powers stable operation control complexity DCM mode low-voltage stress main switches two-switch flyback converter topology flyback microinverter hybrid control scheme unfolding-type interleaved two-switch flyback inverter

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Current source back-to-back converter for wind energy conversion systems

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IET RENEWABLE POWER GENERATION 2016年第10期10卷 1552-1561页

作者： Abdelsalam, Ibrahim Adam, Grain Philip Williams, Barry W. Univ Strathclyde Dept Elect & Elect Engn 204 George St Glasgow Lanark Scotland Arab Acad Sci & Technol & Maritime Transport Elect Power Dept Cairo Egypt

This study proposes a new back-to-back current source converter (BTB-CSC) suitable for medium-voltage high power wind energy conversion systems (WECSs). It employs a dual three-phase permanent magnet synchronous generator and two current source inverters with a phase-shift transformer at the grid side. The proposed BTB-CSC has the following advantages: reduced power circuit and control complexity;low switching losses (zero switching losses at the inverter side);and independent control of active and reactive powers. Power system computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) simulations are used as to assess the steady state and dynamic behaviour of the proposed system under different operating conditions. It is shown that the proposed WECS can ride-through ac faults. Experimental results from scaled prototype of the proposed WECS are used to validate the simulations.

关键词： wind power direct energy conversion permanent magnet generators synchronous generators invertors power transformers power grids reactive power control back-to-back current source converter BTB-CSC medium-voltage high power wind energy conversion systems WECS dual three-phase permanent magnet synchronous generator current source inverters phase-shift transformer grid side reduced power circuit control complexity low switching losses zero switching losses inverter side independent control reactive powers PSCAD-EMTDC simulations ac faults

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A SAFE COMMUNICATION-SYSTEM FOR WHEELCHAIR-MOUNTED MEDICAL ROBOTS

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COMPUTING & control ENGINEERING JOURNAL 1995年第5期6卷 216-221页

作者： DAVIES, B HIBBERD, R Dept. of Mech. Eng. Imperial Coll. of Sci. Technol. & Med. London UK

When a powered medical manipulator is added to a motorised electric wheelchair, the result is a system which can be safety critical for the user. When a number of other systems, such as environmental controllers, displays and navigation systems are incorporated into the overall systems, the complexity of central can further affect safety. The solution to these problems has resulted in the development of a new safe communication system for wheelchair mounted manipulator systems called Multiple-Master, Multiple-Slave (M3S). This work has been carried out as part of a consortium funded by the European TIDE programme.

关键词： manipulators safety-critical software wheelchair mounted manipulator systems Software engineering techniques control complexity environmental controllers medical computing motorised electric wheelchair Multiple-Master Multiple-Slave navigation systems wheelchair mounted medical robots safe communication system Biology and medical computing Manipulators M3S Health and safety aspects wheelchair-mounted medical robots safety critical control engineering computing powered medical manipulator biomedical equipment computerised control Biological and medical control systems

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