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Skeleton and Infill (SI) housing system is considered as a significant path of sustainably prolonging building life by improving structural durability and infill variability for its nature that the skeleton system is fixed, while the infill system could be rebuilt to satisfy users’ changing demands in different stage without damaging the skeleton system. The application of a SI housing system involves two new characteristics compared to traditional cast-in-place housing system: components production in factories and site construction are carried out simultaneously; the skeleton system and the infill system are constructed in parallel phases, which increase enormous parallel work. Iterations and rework would increase with the improper handling of parallel works, which lead to higher construction cost and lower participant willingness of stakeholders in SI housing construction delivery process. It is essential to establish a model to clarify the dependencies among major parallel work items and recognize parallel work sets to optimize the construction sequence for stakeholders to strengthen communication and coordination on key work items in a more efficiency way. By conducting investigations into the construction delivery process of typical SI housing projects in China, this paper developed a parallel collaborative mode based on the design structure matrix (DSM) to identify the complex dependencies among major cooperative work items. Furthermore, to provide an optimized parallel collaborative process, graph theory was introduced to find parallel work sets and eliminate repetition and iteration caused by improper work execution sequences. The results provide a guide for stakeholders to make appropriate cooperation strategies in implementing major work items and promoting cooperating efficiency by reducing iteration and rework.

An orthogonal dispersive spectral-domain optical coherence tomography (SDOCT) system based on a spectrometer consisting of a high spectral resolution virtually-imaged phased array (VIPA) and a low resolution diffraction grating is developed. Two-dimensional (2D) dispersion generated by the combination of the VIPA and the grating in conjunction with a 2D CCD leads to an improved performance of the spectrometer. Ultrahigh spectral resolution of 0.002 nm within a free spectrum range of 50 nm is realized, providing the spectrometer with a spectral sampling rate up to ~10(5). The developed SDOCT realizes an imaging depth over 80 mm, which is the longest depth range ever achieved by SDOCT. The increased spectral sampling rate also results in a high signal-to-noise ratio of the SDOCT system. The application of the developed system is further illustrated by quantitative phase imaging of a glass plate and an optical lens.

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