Experiments and computational approaches are of great importance in all scientific and engineering disciplines. To enable continued progress and further development, more work on experimental methods and computational procedures is needed.

Scientific and technological developments were in ancient times mainly based on observations of natural occurrences. Later on, basically during the last five hundred years or so, theoretical analysis using powerful mathematical principles started to occur, culminating in the progress made during the first half of the last century. These resulted in the emergence of numerical methods that nowadays permeate all ranges of science and technology. At the same time, experimental techniques underwent remarkable improvements, becoming more sophisticated and refined, while liable to handle accurately and reliably large amounts of data. It can be seen that because of their increasing improvements, experimental techniques are becoming more and more multifaceted and complex so that both the operation of the apparatus as well as the collection of the data can only be achieved with the assistance of computers. The huge amount of data obtained needs to be processed by means of computational methods.

Accurate experimental tests are more important than ever because of the increasing sophistication of numerical schemes developed for highly non-linear problems. The reliability of experimental data in these cases is vital for the validation of those schemes and to inspire confidence in the experimental data. Numerical methods play an increasingly important role in experiments, not only to process and interpret the data, but also to assist in the design of a programme to reduce the number of tests, for instance.

The combined use of a computer simulated experiment aimed at the identification of system parameters through an optimisation procedure is a major development which emerged due to the dramatic evolution of computer hardware and simulation software codes. Computer simulation can indeed provide powerful insight into the behaviour of systems and processes as well as many other scientific and engineering problems. The use of simulation software for instance has led to the emergence of “virtual prototyping” which is widely used in the manufacturing industry to reduce expensive and time-consuming hardware models.

Nowadays, even the evolution of some parameters can be followed up; the experiment itself continuously analysing the measurements obtained. This allows the monitoring of different types of components and gives useful information about preventative maintenance of complex systems.

The main objective of the International Journal of Computational Methods and Experimental Measurements is to provide a forum to the scientific and engineering communities for the presentation and discussion of the interaction and complementary factors of Computational Methods and Experiments, with emphasis on their reciprocal and mutually beneficial integration. The Journal will also focus on the following areas:

a) Experimental measurement techniques which have gradually become very sophisticated

b) Computer software, able to simulate very complex behaviour

c) Optimization procedures applied to the interaction between experimental and numerical data

The Journal has evolved from a series of very successful initiatives taken by the Wessex Institute of Technology over the last 30 years or so, which include several major conferences; including one with the same title as the Journal and others on materials, structural and mechanical systems. Most of the papers submitted at those meetings can be seen in WIT’s eLibrary (http://library.witpress.com). The Journal attempts to provide room for further development of these ideas in a more comprehensive way.

The Editors, 2013

The paper presents an experimental investigation into the internal blast loading of open-ended, seamless, mild steel cylinders. A series of 10 trials were conducted on explosively loaded vessels using increasing masses of PE4 explosive. The objective of these trials was to determine the maximum circumferential strain induced in the cylinder wall as a result of the blast loading and also to determine the minimum amount of explosive required to cause wall failure in the cylinder. A cylindrical-shaped charge was detonated at the centre of the cylinder as this was more likely to produce a symmetrical blast wave than a spherical-shaped charge. The response of the cylinder with increasing charge size goes from large plastic deformation to failure by propagation of longitudinal cracks in the region of localized wall thinning. It is thought that the localized wall thinning is a result of unstable modal vibration and this is confi rmed by instability analysis. This investigation has allowed insight into the failure process of these structures not previously examined under the given loading conditions. The data generated in these trials has been used successfully to validate numerical and theoretical models of the cylinder response to impulsive loading.

Military operations performed by UN and NATO forces within the framework of stabilization missions revealed the weak points of the equipment utilized by these organizations. It turned out that one of the most dangerous threats is posed by partisan missiles equipped with cumulative heads. These missiles are mostly based on a Soviet solution and allow the penetration up to 300 mm of reinforced steel. This fact results in a serious problem which concerns the relevant protection against such a type of weapon. One of protection methods against cumulative missiles is the application of rod armours.

The present paper concentrates on the analysis of the impact of a missile with a cumulative head (type PG-G7) into armour made of rods with a circular cross-section. Four options of rods arrangements were considered. A short characteristic of an analysed object was presented. A principle of operations of a missile with the specifi cation of its sensitive elements was described from the perspective of origi-nating of a cumulative stream. The stages of constructing a numerical model as well as the applied simplifi cations of geometry and initial boundary conditions were presented. On the basis of the obtained results, a degree of destruction of key elements of the missile was estimated. The fi gures revealing defor-mation of the missile and the maps of stresses in these elements were presented. In the summary section, an infl uence of a degree of the impact of a missile type PG-G7 into an armour made of rods with circular cross-section on weakening of operation effectiveness of such type of ammunition was determined.

The calculations were realized in LS-Dyna system which is purposed, among others, for fast chang-ing analyses with the use of a fi nite element method. To solve an equation of motion, an explicit integration method included in this system was applied.

Base-isolated buildings experience large horizontal relative displacements during strong earthquakes due to the excessive flexibility that is purposely incorporated, through seismic bearings, at their bases. When the available clearance around a base-isolated building is limited, there is a possibility of the building pounding against the surrounding moat wall or adjacent structures. Considering the nonlinearities involved in this structural impact problem, it is evident that the effects of potential pounding on the overall seismic response of base-isolated buildings during earthquake excitations should be investigated numerically through appropriate simulations. Object-oriented programming (OOP), design patterns (DPs), and the Java programming language have been utilized in order to design and implement a flexible and extendable software application that can be effectively used to perform the necessary numerical simulations and parametric studies of base-isolated buildings that may experience structural poundings during earthquake excitations. The aim of this paper is twofold: (i) to explain the significant advantages of utilizing OOP, DPs, and Java in structural analysis software and (ii) to use the developed software to study earthquake-induced poundings of base-isolated buildings.

A simplified approach is proposed and used to study the TiO2 nanoparticle transport and diffusion in an exposure chamber. This exposure chamber is used to assess lung toxicity in rats resulting from the inhalation of airborne nanoparticles. The simplified approach uses computational fluid dynamics (CFD) commercial software. The mathematical model for airflow is based on the three-dimensional Reynoldsaveraged Navier–Stokes equations with turbulence modeling. The mathematical model for airborne nanoparticles transport is based on assumptions such that their motions are similar to those of a singlesized diameter distribution of a passive contaminant. This model is valid as long as the nanoparticle concentration is low and the particle diameter is small enough that settling is negligible, which is the case for the exposure chamber studied. With this model, the diffusion coefficient is a property that plays a significant role in the transport of airborne nanoparticles. The particle diffusion coefficient can be expressed in terms of a friction coefficient, and three possible relationships to model particle diffusion are presented. Their influences on the friction and diffusion coefficients are considered for the particular case of TiO2 nanoparticles. Although all the models studied here predict a decrease in the value of the diffusion coefficient with increasing particle diameter, some significant variations can be observed between the models. A specific diffusion model is selected and then used with the simplified approach. The simplified approach is first validated against available correlations for particle deposition on walls. Correlation for deposition loss rate in the case of a room agrees with numerical prediction for particle diameter between 10 and 200 nm. Particle mass concentration distribution inside the exposure chamber is also studied. The computed concentration distribution is quite uniform inside the exposure chamber and corresponds to single point measurements.

This project offers the opportunity to investigate oscillatory phenomena that can jeopardize the safety of structures of particular importance, using the accelerometers installed on small electromechanical (MEMS) devices known as Motes, which are devices that transmit data remotely without the need of using cable connections. The term ‘Motes’ usually indicates the single node in a Wireless Sensor Network (WSN). Using the accelerometer sensor installed on these tools, it is possible to program a network with numerous sensors to monitor the behavior of the system being tested. The present state of research has made it possible to obtain a prototype sensor by means of which data can be compared with those measured using traditional systems to detect accelerations ( piezoelectric accelerometers). The first step was that of defi ning the calibration procedure. Once the calibration curve has been completed in the laboratory, the single node (Mote) can be programmed for the acquisition of a single physical quantity and can also be scheduled to transmit these values to create a WSN, comprising numerous sensors connected to a central node that acts as a receiver. All programming is done using the nesC language, and it is finally loaded onto the sensor using the TinyOS operating system for the management of the nodes. During the measurements, one of the main problems manifested by these devices was the discharge of the batteries after a prolonged use. This is highly interesting because the ‘offset value’ characteristic of the sensor is influenced by the energy possessed by the batteries. Another problem highlighted by the tests conducted is the low sensitivity of the accelerometers, compared to that of a seismic accelerometer, a feature causing the loss of events with an intensity below a certain threshold. Nevertheless, these systems make it possible to monitor, with very low costs, critical structures that are subject to physical events of particular intensity to prevent disaster

Accurate estimation of discharge in any open channel depends on the suitable accounting of the resistance coefficients. The energy loss is influenced by the channel geometry and flow parameters, which are assumed to be lumped into a single value manifested in the form of resistance coefficients in terms of Manning's n, Chezy's C, and Darcy–Weisbach f. The flow structure for meandering channels is more complex as compared to that of straight channels due to its three-dimensional motion. Consequently, the use of design methods based on straight channels is inappropriate when applied to meandering channels and results in large errors when estimating the discharge. A series of experimental results are presented concerning stage–discharge–resistance relationships for meandering channels with rigid and smooth boundaries. Investigation concerning the loss of energy of flows for meandering channels in terms of variation of Chezy's C due to variation of sinuosity, geometry, and longitudinal slope are studied.A discharge predictive method for meandering channel is proposed that accounts for the variation of roughness with depth of flow in the channel. The performance of the model is evaluated and is found to compare well with other available models.