This year sees an important landmark reached for Strain and the British Society for Strain Measurement, namely 40 years of continuous support for industrial and academic members. The importance of the interchange of research and development information has never been of greater importance, with the rapidly advancing technologies threatening to leave the uninformed behind. The society encourages cooperation at all levels and between widely different branches of engineering. Strain now has an editorial board with members from 12 countries, showing the wide appeal and influence of the journal. Much has been written recently about the developments of the publication of Strain. We now have a very high-quality journal that is read worldwide. This issue of Strain contains two full papers, two technical notes and a tutorial. Two of the papers deal with sensors in a generic fashion. The first by Sodano et al., suggests a novel means of energy harvesting using the piezoelectric effect. At present, the idea of using wireless technology in conjunction with sensors to eliminate problems brought about by ‘wiring’ is gaining much attention. The advantages of such devices are most greatly exploited in a structural health monitoring or machine condition monitoring context. Applications such as embedded sensors in composite structures, inaccessible locations such as in large civil and offshore structures and in particular large rotating machinery such as wind turbines come to mind as suitable candidates for wireless sensors. The wireless sensors can be remotely interrogated with minimal effect on the structure. The only difficulty is powering the sensor. Batteries are bulky, have a finite lifespan and also require wiring; therefore it is desirable to define a means of ‘self-powering’. The paper defines a means of obtaining power by the conversion of mechanical energy from the motion of the structure to electrical energy to power the sensor. A model of the energy that can be produced was developed in the paper and validated using a non-homogeneous cantilever beam. The experimental study showed that the power-harvesting exercise produced damping in the beam where the energy was stored rather than dissipated into the structure. The second paper by Overton and Worden deals with sensor placement to optimise fault detection in a structure. The paper uses an ant colony metaphor to determine optimum sensor placement for the location and classification of impacts on a composite panel using a neural network. The ant colony metaphor is based on the idea of ants foraging for food using the shortest path by tracking a pheromone trail deposited by other ants. The composite panel used in the work simulated an aircraft skin and was instrumented with 17 piezoceramic strain sensors, which were used initially to train the neural network. The ant colony technique was used to optimise the positioning of three sensors and then six sensors. In both cases, the ant colony approach outperformed a genetic algorithm. The work in this paper will be useful in reducing the amount of computational effort used in structural health monitoring, as optimisation reduces the number of sensors necessary for accurate fault location and hence reduces costs associated with online monitoring. The technical note by Guntaka et al. deals with a new recording medium in the full-field analysis area of holographic interferometry. The new material is self-developing and has the potential to facilitate real-time holographic inspections. The technique was validated on a thick PVC pipe subjected to internal pressure. The technical note by Noroozi et al. deals with the use of neural networks in conjunction with photoelastic data. FEA is used to train the neural network and then the technique is applied in an inverse fashion to derive the relative retardation obtained from photoelastic data and hence the value of the applied load. This work provides an important first step in combining FEA and photoelasticity to produce a hybrid technique for stress analysis. The tutorial by Truman will be of value to all stress analysts and deals with the application of tensor elasticity to isotropic bodies. Two well-known problems in plane elasticity are cited as examples and the reader is shown how the solutions for these problems are derived. The tutorial follows on from the first in the series presented in the November 2003 issue of Strain. To conclude, the journal Strain and the Society have offered much information and support through the hard work of many dedicated members and thanks goes to all that have contributed so much over the last 40 years. Some have been active throughout virtually all of that time, which is a tremendous show of dedication and enthusiasm for their chosen field.