A six-phase transverse-flux-reversal linear machine for low-speed reciprocating power generation

In this paper, a 6-phase permanent-magnet flux-reversal linear machine for low-speed reciprocating power generation is presented. By increasing the phase number, the phase current is reduced for the same rated power which results in a lower ohmic loss. In addition, the thrust force ripple can be reduced accordingly. By borrowing the transverse-flux concept, the electric loading and the magnetic loading is decoupled and the thrust density can be improved accordingly. The stator of the proposed machine adopts the modular design, and each phase is magnetically decoupled with each other which gives more flexibility and controllability of the generator. Based on the same topology, the proposed machine can be extended to a machine with an arbitrary number of phase to suit different applications.published_or_final_versio

A transverse flux permanent magnet linear generator for hybrid electric vehicles

Article: TD-007358This paper presents a transverse flux permanent magnet (TFPM) linear generator for the free-piston generation application, which not only possessing the merits of the existing TFPM machine, but also providing a simple structure which is essential for power generation with maintenance-free operation. Also, the machine configuration is optimized such that the induced voltage is maximized while the cogging force is minimized. Hence, a 2-phase linear TFPM is resulted, which is well supported by performance analysis.published_or_final_versio

VSPN: VANET-based Secure and Privacy-preserving Navigation

postprin

Privacy-preserving advance power reservation

Smart grid is considered to be the next generation power system. Integrating information and communication technology, power electronics, and power system technologies, smart grid reduces excess power generation by better matching power generation with customer demands, and facilitates renewable power generation by closely monitoring renewable energy source status. Such a large-scale network may be subject to various attacks. In particular, authentication and user privacy preservation are considered two major security concerns. In this article, we first highlight the importance of smart grid security. Next we introduce a new power request paradigm in which a customer is allowed to submit a power usage plan in advance. We then propose a secure and privacy-preserving power request scheme as a solution to this problem. To achieve the privacy-preserving property, our scheme employs two cryptographic techniques: anonymous credential and blind signature. We conclude this article by discussing the security and performance issues of our proposed scheme. © 1979-2012 IEEE.published_or_final_versio

Security and privacy issues for inter-vehicle communications in VANETs

Vehicular ad hoc network (VANET) is an emerging type of networks to allow vehicles on roads to communicate for driving safety. An vehicle can broadcast messages (e.g. accident information) to other vehicles. These messages may have impact on other vehicles as well as the traffic control system, so all messages must be signed and authenticated. On the other hand, privacy should be enforced while the real identity of the sender should be traceable by authorized party. In this poster, we first discuss the limitations of existing solutions. In particular, we describe an impersonation attack to one of the schemes, highlight the problem of communications overhead, and effectiveness of the message verification procedure. Then, we present the main ideas of our proposed scheme which can be shown to be secure and more effective than existing schemes.published_or_final_versionThe 6th Annual IEEE Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks Workshops (SECON Workshops '09), Rome, Italy, 22-26 June 2009. In Proceedings of the 6th IEEE SECON Workshops, 2009, p. 1-

SPECS: Secure and privacy enhancing communications schemes for VANETs

This journal issue entitled: Advances in Ad Hoc Networks (I)Vehicular ad hoc network (VANET) is an emerging type of networks which facilitates vehicles on roads to communicate for driving safety. The basic idea is to allow arbitrary vehicles to broadcast ad hoc messages (e.g. traffic accidents) to other vehicles. However, this raises the concern of security and privacy. Messages should be signed and verified before they are trusted while the real identity of vehicles should not be revealed, but traceable by authorized party. Existing solutions either rely heavily on a tamper-proof hardware device, or cannot satisfy the privacy requirement and do not have an effective message verification scheme. In this paper, we provide a software-based solution which makes use of only two shared secrets to satisfy the privacy requirement (with security analysis) and gives lower message overhead and at least 45% higher successful rate than previous solutions in the message verification phase using the bloom filter and the binary search techniques (through simulation study). We also provide the first group communication protocol to allow vehicles to authenticate and securely communicate with others in a group of known vehicles. © 2010 Elsevier B.V. All rights reserved.postprin

Maximum power point tracking control of a linear magnetic-geared generator for direct-drive wave energy conversion

This paper deals with control of a linear magneticgeared permanent-magnet generator for wave power generation using maximum power point tracking (MPPT) algorithm. Firstly, the linear magnetic-geared permanent-magnet generator structure is presented. The machine modeling is established based on the finite element analysis (FEA). Secondly, by analyzing the dynamic model of the wave power, the MPPT algorithm for directdrive wave power generation is discussed. Then, the performance for maximizing wave power absorption is verified and evaluated by the circuit simulator. The results verify that the MPPT algorithm is valid for the direct-drive wave power generation.postprin

A low-speed linear harmonic generator for grid-tied and stand-alone operation using hybrid excitation topology

Paper no. BP-09Since intermediate mechanical conversion mechanisms for speed, torque and motion conversion can be entirely eliminated, the direct-drive wave power generation attracts more and more attention [1]. Among various proposed generators, the permanent-magnet (PM) vernier generator is considered as a viable solution for the wave energy harvesting. This generator can efficiently harness this low-speed and high-power energy source via a so-called vernier effect by utilizing the effective harmonic magnetic field [2]. However, since only PMs are engaged for field excitation and the harmonic magnetic field is adopted, it is incapable to provide a flexible voltage control and power factor improvement. Moreover, the voltage regulation is incredible high. The purpose of this paper is to design a linear harmonic generator for producing electricity in a wave farm. Except for the PM excitation, the proposed generator is equipped with a set of DC field winding for the hybrid excitation. With this merit, the proposed generator exhibits a satisfactory performance for voltage regulation and power factor improvement which is desirable for both grid-tied and stand-alone operation [3]. © 2015 IEEE.published_or_final_versio

PASS: Privacy-preserving authentication scheme for smart grid network

A smart grid power system is capable of adjusting the amount of electricity generated based on real-time requests from the smart meters of customers, thus avoiding excess electricity generation and facilitating reliable and effective transmission of electricity. To ensure that requests are sent from a valid user, all request messages must be authenticated. On the other hand, by analyzing the electricity usage pattern of a customer, the daily habit of the customer, such as when he is away, may be revealed. Thus, a proper privacy preserving mechanism has to be adopted. This paper attempts to develop a scheme to address these two seemingly contradicting requirements efficiently. By using a tamper-resistant device at the smart appliance and pseudo identities, we derive a privacy preserving authentication scheme to solve the problem. The authentication process is made very efficient by means of Hash-based Message Authentication Code (HMAC). Through simulation, we show that with our scheme, the transmission and signature verification delay induced are very small and the message overhead is only 20 bytes per request message. With our efficient verification process, even under attack, the substation can effectively drop all attack messages, allowing 6 times more valid messages to reach the control center when compared to the case without any verification. Thus our scheme is both efficient and effective. © 2011 IEEE.published_or_final_versionThe 2nd IEEE International Conference on Smart Grid Communications (SmartGridComm 2011), Brussels, Belgium, 17-20 October 2011. In Proceedings of the 2nd Smartgridcomm, 2011, p. 196-20