Ronen Barak

Construction safety training using immersive virtual reality

Construction workers’ ability to identify and assess risks is acquired through training and experience and is among the key factors that determine their behaviour and thus their safety. Yet researchers have questioned the effectiveness of conventional safety training. This research tested the hypotheses that safety training in a virtual reality (VR) construction site would be feasible and more effective, in terms of workers’ learning and recall in identifying and assessing construction safety risks, than would equivalent training using conventional methods. Sixty-six subjects were provided training in construction safety and their safety knowledge was tested prior to the training, immediately afterward, and one month later. Half of the subjects received traditional classroom training with visual aids; the other half were trained using a 3D immersive VR power-wall. Significant advantage was found for VR training for stone cladding work and for cast-in-situ concrete work, but not for general site safety. VR training was more effective in terms of maintaining trainees’ attention and concentration. Training with VR was more effective over time, especially in the context of cast-in-situ concrete works. Given the need for improved training and the advantages of training using VR, incorporation of VR in construction safety training is strongly recommended.

Quantum fast Fourier transform and quantum computation by linear optics

Using the quantum fast Fourier transform in linear optics the input mode annihilation operators {a0,a1,...,as−1} are transformed into output mode annihilation operators {b0,b1,...,bs−1}. We show how to implement experimentally such transformations based on the Cooley-Tukey algorithm, by the use of beam splitters and phase shifters in a linear optical system. Optical systems implementing 1,2, and 3 qubits discrete Fourier transform (DFT) are described, and a general method for implementing the n-qubit DFT is analyzed. These transformations are used on various input radiation states by which phase estimation and order finding can be computed.

Unique Requirements of Building Information Modeling for Cast-in-Place Reinforced Concrete

The building information modeling BIM tools that have matured for structural steel and precast concrete construction are not suitable for production modeling of cast-in-place CIP reinforced concrete structures. The main reason is that CIP structures are monolithic in nature, as opposed to the discrete objects that are typical of steel and precast. A consortium of 12 major contractors and design firms collaborated over a one-year period to formulate the functional requirements for development of a BIM tool for cast-in-place reinforced concrete. The functional requirements were derived from a process model used to scope and understand the processes surrounding reinforced concrete design and production. The functional requirements were finally expressed as a set of object schemas, defining relations, methods, and attributes needed. These are essential for software companies to incorporate in their BIM tools to provide for the unique needs of modeling CIP structures.

Photon statistics and entanglement in coherent-squeezed linear Mach-Zehnder and Michelson interferometers

Photon statistics effects are analyzed for Mach-Zehnder and Michelson interferometers in which a strong coherent state is inserted into one input port and a squeezed vacuum is inserted in the other input port. We study the effects related to entanglement, for the general case, by using Zassenhauss perturbation theory as a function of the squeezing parameter. For the special case in which the strong coherent state exits fully through one output port while the squeezed vacuum exits through the other “dark” output port, the Lie group disentangling method is used. For this case we show that the signal can be amplified with sub-Poissonian photon statistics.