Abstract
Indoor radon activities were measured during a period of 6 months, as well as several physical environmental variables (temperature, pressure, humidity and rainfall). The location was a small room at an administrative building of the University of Coimbra, usually undisturbed by human activities and situated over bedrock of low-uranium Triassic red sandstones. A low average activity of radon was observed (36 Bq m(-3)), however showing a very well marked daily periodicity (10 +/- 5 Bq m(-3)), with maximum values occurring more frequently between 9 and 10 a.m. Daily variations are shown to have no relation with earth tides, and their amplitudes exhibit a significant correlation with outdoor temperature; no dependence on barometric pressure was found. Rainfall disturbs the observed daily radon cycles through a strong reduction of their amplitude, but has no effect on the long-term variability of the gas concentration.

Abstract
This study was carried out to improve diagnosis and prediction of geomaterials status from coastal protection structures. A methodology is proposed for the characterization of rock materials and management of the structures. The characterization was organized in different phases: i) visual inspection; ii) field techniques to study geologic-geotechnical features; iii) in situ measurement of geomechanical parameters; and iv) development of GIS-based mapping and assessment of the block materials. The results obtained allowed to define a geotechnical zonation for the structure armor layer, according to the type of geomaterial source, weathering/degradation grade and geomechanical rebound values. The GIS project developed, combined an applied cartography of the groins' superficial layer with the results of the field techniques. The interactive base included the pilot case presented in this work, from Espinho coastal area (NW Portugal, Iberian Peninsula), which comprises four different sectors. The results of this work, support the need to apply geomechanic concepts to coastal structures, since they allow the evaluation of deterioration levels and improve the planning of intervention works. This methodology contributes to ameliorate the efficiency of monitoring and maintenance, in an economically beneficial mode. © ISRM International Symposium on Rock Mechanics, SINOROCK 2009.

Abstract
This study was carried out to develop a systematic methodology for the analysis of coastal protection structures in a GIS database project. This work contributes to ameliorate the efficiency of monitoring and maintenance, in an economically beneficial mode. Low-level aerial surveys were conducted from a light aircraft, providing high-resolution digital images Suitable for armour layer integrity analysis. Combining photogrammetric and field techniques, this research aims to define an applied cartography for geomaterials characterisation in hydraulic works. This research comprehends different phases: i) Visual inspection; ii) field techniques to study geologic-geotechnical features; iii) in situ measurement of geomechanical parameters; and iv) development of GIS mapping and assessment of the block materials. The GIS project incorporates high-resolution aerial imagery surveys and the results of the field techniques applied for the structures' cartography. The interactive base included the pilot case presented in this work, from Espinho coastal area (NW Portugal), which comprises five sectors. Based on the described methodology, different geomaterials were recognised, providing an evaluation of the current condition of the structure and the revetment material status. The results obtained allowed to define a geomaterial zonation for the structures' armour layer, according to the type of rock source, weathering/degradation grade and in situ, geomechanical tests. Also, the outcome established by these results indicates the need for repairing/maintenance works in some parts of the studied structures. This guidance may be helpful during pre-design or planning assessments, supported by coastal geoengineering concepts. It also generates useful knowledge for repairing recommendations and conceptual coastal management.

Abstract
Shoreline change in the Espinho area ( northwest Portugal) is a chronic problem. The present study takes advantage of geographical information system (GIS) tools to contribute to the knowledge of the geologic and geomorphological dynamics of the Espinho shoreline. A GIS-based monitoring project was compiled, which gathers information on all coastal works located along the Espinho shoreline, focusing especially on construction, monitoring, and repair aspects. Shoreline change was analyzed using the ArcGIS extension "Digital Shoreline Analysis System'' (DSAS) to understand this important aspect of coastal management. This work also emphasizes the importance of geotechnical assessment of coastal protection structures in diagnosing their degree of damage and/or deterioration so that one can plan more efficient maintenance works. Our results indicate a general trend of erosion to the south and accretion to the north of the Espinho coastal area. Geoengineering characterization of the Paramos groin defines three main zones for the armor block materials (i.e., Zones I, II/III, and IV), which show, respectively, very low, medium to high, and low deterioration levels.

Abstract
In this technical brief, a new subspace state space system identification algorithm for multi-input multi-output bilinear systems driven by white noise inputs is introduced. The new algorithm is based on a uniformly convergent Picard sequence of linear deterministic-stochastic state space subsystems which are easily identifiable by any linear deterministic-stochastic subspace algorithm such as MOESP, N4SID, CVA, or CCA. The key to the proposed algorithm is the fact that the bilinear term is a second-order white noise process. Using a standard linear Kalman filter model, the bilinear term can be estimated and combined with the system inputs at each iteration, thus leading to a linear system with extended inputs of dimension m(n + 1), where n is the system order and m is the dimension of the inputs. It is also shown that the model parameters obtained with the new algorithm converge to those of the true bilinear model. Moreover, the proposed algorithm has the same consistency conditions as the linear subspace identification algorithms when i -> infinity, where i is the number of block rows in the past/future block Hankel data matrices. Typical bilinear subspace identification algorithms available in the literature cannot handle large values of i, thus leading to biased parameter estimates. Unlike existing bilinear subspace identification algorithms whose row dimensions in the data matrices grow exponentially, and hence suffer from the "curse of dimensionality," in the proposed algorithm the dimensions of the data matrices are comparable to those of a linear subspace identification algorithm. A case study is presented with data from a heat exchanger experiment.

Abstract
In this paper the Wiener-Hammerstein system proposed as a benchmark for the SYSID 2009 benchmark session is identified as a bilinear discrete system. The bilinear approximation relies on both facts that the Wiener-Hammerstein system can be described by a Volterra series which can be approximated by bilinear systems. The identification is performed with an iterative bilinear subspace identification algorithm previously proposed by the authors. In order to increase accuracy, polynomial static nonlinearities are added to the bilinear model input. These Hammerstein type bilinear models are then identified using the same iterative subspace identification algorithm. © 2009 IFAC.