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The constitutive thermo‐hydro‐mechanical equations of fractured media are embodied in the theory of mixtures applied to three‐phase poroelastic media. The solid skeleton contains two distinct cavities filled with the same fluid. Each of the three phases is endowed with its own temperature. The constitutive relations governing the thermomechanical behavior, generalized diffusion and transfer are structured by, and satisfy, the dissipation inequality. The cavities exchange both mass and energy. Mass exchanges are driven by the jump in scaled chemical potential, and energy exchanges by the jump in coldness. The finite element approximation uses the displacement vector, the two fluid pressures and the three temperatures as primary variables. It is used to analyze a generic hot dry rock geothermal reservoir. Three parameters of the model are calibrated from the thermal outputs of Fenton Hill and Rosemanowes HDR reservoirs. The calibrated model is next applied to simulate circulation tests at the Fenton Hill HDR reservoir. The finer thermo‐hydro‐mechanical response provided by the dual porosity model with respect to a single porosity model is highlighted in a parameter analysis. Emphasis is put on the influence of the fracture spacing, on the effective stress response and on the permeation of the fluid into the porous blocks. The dual porosity model yields a thermally induced effective stress that is less tensile compared with the single porosity response. This effect becomes significant for large fracture spacings. In agreement with field data, fluid loss is observed to be high initially and to decrease with time. Key Points Thermo‐hydro‐mechanical equations of fractured media The model is calibrated from the thermal outputs of two HDR reservoirs Simulation of circulation tests at Fenton Hill HDR reservoir

Suffusion is a complex phenomenon characterized by a selective migration of the fine particles under the effect of three coupled processes: detachment, transport and possible filtration of the fine fraction. With the objective to reproduce the kinetics of the suffusion process, a new energy-based constitutive relationship, inspired from the energy-based approach, is proposed. Moreover, this energy-based relationship is compared with other constitutive relationships inspired from the shear stress-based approach and the power-based approach. Each predicted eroded mass evolution is consistently compared against experimental measurements. For each individual specimen, the shear stress-based constitutive relationship tackles well the initiation of the suffusion process but overestimates the development of the process. On the other hand, both the energy-based and the power-based constitutive relationships can reproduce reasonably well the evolution of the cumulative eroded mass. Finally, the intrinsic quality (i.e., independent of the sample size and of the loading path, at least at the laboratory scale) of all parameters is examined and advantages and drawbacks of each approach are also highlighted.

Internal erosion, characterized by the migration of soil particles within hydraulic earth structures due to seepage, is a significant global concern for risk management and maintenance. Among various mechanisms contributing to internal erosion, suffusion emerges as a prominent process. It involves the simultaneous detachment, transport, and potential self-filtration of fine particles through the pore network, leading potentially to a change in permeability and shear strength. Thus, investigating the link between permeability and microstructure is a key to achieve a better understanding of suffusion and to predict its consequences on the soil’s permeability. The proposed methodology involves generating discrete element method-based samples, characterizing their constriction size distribution, and computing permeability using fast Fourier transform. While the Kozeny-Carman model was initially developed for stable microstructures, it may not apply to suffusion due to microstructural evolution. Thus, a modified approach is introduced, incorporating a characteristic constriction diameter computed from the constriction size distribution. This modified model is being compared against the original Kozeny-Carman one on fourteen gap-graded specimens. Encouraging results are herein being obtained so that the modified approach will be later used on flow modified specimens.

Accessing the thermo-mechanical response of large deep Hot Dry Rock (HDR) reservoirs during geothermal extraction remains a challenging task that can be comprehended with numerical tools. Of crucial importance to the economic viability of these HDR reservoirs is the knowledge of thermal output evolution, fluid excessive pressure and induced thermal stress, at various steps of the circulation tests. Thermal recovery from a HDR reservoir, viewed as a deformable fractured medium, is investigated with a focus on the assumption of Local Thermal Non-Equilibrium (LTNE). To this end, a fully coupled finite element formulation for a thermo-elastic fractured medium in LTNE is developed (Gelet et al. 2013). Hydraulic diffusion, thermal diffusion, forced convection and deformation are considered in a two-phase framework, the solid phase being made by impermeable solid blocks separated by saturated fractures. Each of the two phases is endowed with its own temperature. The resulting system of equations is used to address a generic HDR reservoir subjected to temperature and pressure gradients. A change of time profile of the outlet fluid temperature is observed as the fracture spacing increases, switching from a single-step pattern to a double-step pattern, a feature which is viewed as characteristic of established LTNE. A dimensionless number is proposed to delineate between Local Thermal Equilibrium (LTE) and non-equilibrium. This number embodies local physical properties of the mixture, elements of the geometry of the reservoir and the production flow rate. All the above properties being fixed, the resulting fracture spacing threshold between LTNE and LTE is found to decrease with increasing porosity. The thermally induced effective stress is tensile near the injection well, illustrating the thermal contraction of the rock, while the pressure contribution of the fracture fluid is negligible during the late period.

To evaluate in unselected patients imaged under routine conditions the co-registration accuracy of elastic fusion between magnetic resonance (MR) and ultrasound (US) images obtained by the Koelis Urostation™. We prospectively included 15 consecutive patients referred for placement of intraprostatic fiducials before radiotherapy and who gave written informed consent by signing the Institutional Review Board-approved forms. Three fiducials were placed in the prostate under US guidance in standardized positions (right apex, left mid-gland, right base) using the Koelis Urostation™. Patients then underwent prostate MR imaging. Four operators outlined the prostate on MR and US images and an elastic fusion was retrospectively performed. Fiducials were used to measure the overall target registration error (TRE3D), the error along the antero-posterior (TREAP), right-left (TRERL) and head-feet (TREHF) directions, and within the plane orthogonal to the virtual biopsy track (TRE2D). Median TRE3D and TRE2D were 3.8-5.6 mm, and 2.5-3.6 mm, respectively. TRE3D was significantly influenced by the operator (p = 0.013), fiducial location (p = 0.001) and 3D axis orientation (p<0.0001). The worst results were obtained by the least experienced operator. TRE3D was smaller in mid-gland and base than in apex (average difference: -1.21 mm (95% confidence interval (95%CI): -2.03; -0.4) and -1.56 mm (95%CI: -2.44; -0.69) respectively). TREAP and TREHF were larger than TRERL (average difference: +1.29 mm (95%CI: +0.87; +1.71) and +0.59 mm (95%CI: +0.1; +0.95) respectively). Registration error values were reasonable for clinical practice. The co-registration accuracy was significantly influenced by the operator's experience, and significantly poorer in the antero-posterior direction and at the apex.

Objective To evaluate whether focal abnormalities (FAs) depicted by prostate MRI could be characterised using simple semiological features. Methods 134 patients who underwent T2-weighted, diffusion-weighted and dynamic contrast-enhanced MRI at 1.5 T before prostate biopsy were prospectively included. FAs visible at MRI were characterised by their shape, the degree of signal abnormality (0 = normal to 3 = markedly abnormal) on individual MR sequences, and a subjective score (SS 1  = probably benign to SS 3  = probably malignant). FAs were then biopsied under US guidance. Results 56/233 FAs were positive at biopsy. The subjective score significantly predicted biopsy results ( P  < 0.01). As compared to SS 1 FAs, the odds ratios (OR) of malignancy of SS 2 and SS 3 FAs were 9.9 (1.8–55.9) and 163.8 (11.5–2331). Unlike FAs’ shape, a simple combination of MR signal abnormalities (into “low-risk”, “intermediate” and “high-risk” groups) significantly predicted biopsy results ( P  < 0.008). As compared to “low risk” FAs, the OR of malignancy of “intermediate” and “high-risk” FAs were 4.5 (1.1–18.4) and 52.7 (6.8–407) in the overall population and 5.4 (1.1–27.2) and 118.2 (6.1–2301) in PZ. Conclusions A simple combination of signal abnormalities of individual MR sequences can significantly stratify the risk of malignancy of FAs, holding promise of a more standardised interpretation of MRI by readers with varying experience. Key Points • Using multiparameter(mp)-MRI, experienced uroradiologists can stratify the malignancy risk of prostatic lesions • The shape of prostatic focal abnormalities in the peripheral zone does not help predicting malignancy. • A simple combination of findings at mp-MRI can help less-experienced radiologists

Background: To analyze data on patients with localized prostate cancer who were treated with complete high-intensity focused ultrasound (HIFU) prospectively captured within a voluntary HIFU user database (@-Registry). Methods: The @-Registry includes data from consecutive patients treated with Ablatherm (EDAP-TMS) HIFU at nine European Centres during the period 1994 and 2009. For this analysis, the data repository was reviewed for information on patients with localized prostate cancer (T1–T2) treated with complete (whole-gland) HIFU on the basis of an anterior-posterior prostate height of ⩽24 mm and a treated volume >120% of the prostate volume. Patients were regularly followed with PSA measurement and biopsy. Biochemical failure was defined for this study as PSA nadir +2 ng ml −1 (Phoenix definition). Disease-free survival was based on a biopsy, retreatment and biochemical data. Patients were risk group-stratified using the D'Amico classification system. Results: The median follow-up was 2.8 years for the 356 patients included in the analysis. The majority could be classified as either low (44.9%) or intermediate risk (39.6%); 14.6% patients were classified as high risk. The median (mean, s.d.) PSA nadir was 0.11 ng ml −1 (0.78 and 3.6), achieved at a mean (s.d.) of 14.4 (11.6) weeks after HIFU. Follow-up biopsies on 226/356 (63.5%) patients revealed an overall negative biopsy rate of 80.5% (182/226); there was no statistically significant difference in positive biopsy rate by risk group-stratification. Actuarial freedom from biochemical recurrence at 5 and 7 years according to the Phoenix definition was 85% and 79%, respectively. Disease-free progression rates at 5 and 7 years were 64% and 54%, respectively. Conclusions: Whole-gland prostate HIFU as primary monotherapy for localized prostate cancer achieves a recurrence-free survival in short-term analysis as assessed by prostate biopsy and serum PSA endpoints in a majority of patients.

Background: To analyze data on patients with localized prostate cancer who were treated with complete high-intensity focused ultrasound (HIFU) prospectively captured within a voluntary HIFU user database ([at]-Registry). Methods: The [at]-Registry includes data from consecutive patients treated with Ablatherm (EDAP-TMS) HIFU at nine European Centres during the period 1994 and 2009. For this analysis, the data repository was reviewed for information on patients with localized prostate cancer (T1-T2) treated with complete (whole-gland) HIFU on the basis of an anterior-posterior prostate height of less than or equal to 24 mm and a treated volume >120% of the prostate volume. Patients were regularly followed with PSA measurement and biopsy. Biochemical failure was defined for this study as PSA nadir +2 ng ml super(-1) (Phoenix definition). Disease-free survival was based on a biopsy, retreatment and biochemical data. Patients were risk group-stratified using the D'Amico classification system. Results: The median follow-up was 2.8 years for the 356 patients included in the analysis. The majority could be classified as either low (44.9%) or intermediate risk (39.6%); 14.6% patients were classified as high risk. The median (mean, s.d.) PSA nadir was 0.11 ng ml super(-1) (0.78 and 3.6), achieved at a mean (s.d.) of 14.4 (11.6) weeks after HIFU. Follow-up biopsies on 226/356 (63.5%) patients revealed an overall negative biopsy rate of 80.5% (182/226); there was no statistically significant difference in positive biopsy rate by risk group-stratification. Actuarial freedom from biochemical recurrence at 5 and 7 years according to the Phoenix definition was 85% and 79%, respectively. Disease-free progression rates at 5 and 7 years were 64% and 54%, respectively. Conclusions: Whole-gland prostate HIFU as primary monotherapy for localized prostate cancer achieves a recurrence-free survival in short-term analysis as assessed by prostate biopsy and serum PSA endpoints in a majority of patients.

Industrial fuses are composed of metallic elements in compacted quartz sand in a ceramic casing. In case of short circuit, rapid-heating of the metal conducts its melting and dispersion. The current is maintained momentarily by apparition of an electrical arc which create a hole of vaporized material called \"arc channel\". The aim of this work is to evaluate the key phenomena and variables involved in the transfer of the arc energy to the silica filler of the fuse to develop a quantitative procedure of dimensioning. The physical description is inspired by models on laser/matter interaction. Goal is to predict speeds of liquid and gas fronts, surface temperatures, and the pressure induced in the arc channel.