Active noise control (ANC) has been a promising method for noise control and also for other applications such as active increase of absorption and active increase of sound transmission loss of partitions. However, only a few applications have been commercially attractive. At the Technical Research Centre of Finland (VTT) a method to manufacture thin, flat acoustic sensors and actuators (flat microphones and loudspeakers) utilizing ElectroMechanical Film (EMFi) technology has been developed. Flat sensors and actuators can be implemented in ANC applications, where large surfaces should be covered with sensors or anti-sound producing elements. EMFi sensors and actuators are typically 4- to 10-mm-thick elements. They can also be collocated, forming an advanced sensor–actuator combination. Results of research focusing on the use of EMFi technology to increase the sound transmission loss of partitions by active means are presented. By active means the sound transmission loss of the partitions against broadband noise could be increased up to 10 dB in the frequency range 100–350 Hz. Results are new and of great importance, because new ANC technology is being developed. The commercial production of EMFi panel actuators will start in the middle of the year 2000.

Electric bus energy consumption is mainly due to the vehicle traction. Additionally, auxiliary systems such as cabin heating-cooling, air compressor, and power steering consume energy. One way to optimize the consumption is a Driver's Aid System (DAS). Based on the route information, DAS provides the driver the optimal driving suggestions, and simultaneously may optimise the energy use of auxiliary systems. These approaches are discussed in the paper. When the optimal air compressor operation was introduced, vehicle energy consumption was decreased 1.6 %. In addition to guiding the auxiliary devices and the driver, prospects of using DAS as a communication hub for managing buses, their charging and to share information for a bus operator are discussed.

This paper presents a pre-normative roadmap that foresees the developments in the charging of heavy-duty electric vehicles (HD-EVs). It supports and facilitates the future standardization efforts of charging technologies by creating an overview of the popularity of charging technologies and the end users’ needs. The required input for the work was collected using a comprehensive investigation on the available charging technologies and their standardization, reviewing the existing roadmaps and research work, and conducting surveys and interviews of end users and technical stakeholders. According to the findings, a pantograph on the roof of a vehicle and plug-based charging are currently the most used charging interfaces. This trend is likely to continue in the future, since (1) pantographs on vehicle roofs, (2) pantographs on infrastructure, and (3) plugs were graded as charging interfaces with the highest potential by the participants of the technical survey. Static and conductive charging technologies show more potential than dynamic and wireless charging technologies. Nevertheless, inductive charging may be a future charging solution for HD-EVs if the current bottlenecks in the technology can be addressed. These bottlenecks include high prices, slightly lower efficiency, lack of standardization, the maximum achievable power, and safety concerns. Furthermore, interoperability was repeatedly mentioned as the main challenge for today’s charging technologies.

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Feedback control for the active noise cancellation can be done with analog or digital circuitry. Although digital approach is steadily gaining ground, analog control still has its uses. Short control latency is the feature of an analog controller—it has the shortest possible delay. Its drawback is the limited flexibility for adjustable or adaptive solutions. To overcome this, digitally adjustable analog controllers can be used. A potential implementation for such controller uses field programmable analog array (FPAA) technology. With FPAAs both the filter parameters and structure are digitally adjustable, even during the operation. A development environment around the FPAA controller has been devised. It consists of the measurement system, an optimizer that calculates the optimum controller response, programming software, and actual FPAA hardware with its embedded software. The complete system is packaged tightly to a compact form. It can be used for evaluation purposes in acoustics laboratory conditions. Such a system has been evaluated in active noise insulation application. It has proven to operate as simulated and optimized also in real-world tests. The future development of the system includes further miniaturization, controller networking, and possible integration inside the sound insulation system.