In-site Experiment Research Articles

Natural ventilation in large spaces: CFD simplified model validated with full-scale experimental data of Roman Baths

This study addresses the escalating need for energy-efficient and well-ventilated buildings by examining natural ventilation in large spaces. Validation of a CFD model was pursued through in-site experiments at the Roman Baths Museum in Chaves, Portugal. A sensitivity analysis aimed to determine the optimal number of monitoring points for model validation, crucial for establishing procedures in large-volume settings. Findings emphasized the feasibility of using a minimal number of monitored points, notably with a 3 × 3 test point arrangement, showcasing consistent temperature variations with low relative errors (0.50 %–1.75 %). Furthermore, the validated model assessed ventilation performance under diverse operational conditions, revealing slight enhancements in experimental settings, including an increase in air change rate (2.4 vs. 2.2 ACH) and a decrease in buoyancy dominance (Richardson number 197.3 vs. 241.3) compared to design conditions. Quantitative analysis highlighted similar temperature and velocity trends, with greater stratification in experimental conditions (temperature ratios 0.12 to 0.36 vs. 0.10 to 0.32). Qualitative assessments align with the quantitative analysis and enable the identification of stagnation zones and airflow distribution patterns. These findings affirm the methods' reliability in analysing ventilation in large spaces naturally ventilated, validating the model across diverse contexts, despite fewer data points.

Hyporheic exchange and nitrogen cycle processes under the dual effects of flooding and heterogeneous streambed

In this study, we investigated the effects of media heterogeneity and flood processes on hyporheic exchange and nitrogen cycle processes in hyporheic zone adjacent to a natural in-stream gravel bar. We conducted field experiments and set a reactive transport model of surface-groundwater exchange based on the monitoring results. The flood process is obtained based on field monitoring, and the heterogeneous medium field is constructed using the SAR3DC method based on in-site experiment results. The results showed that both the heterogeneity of the medium and the flood process can enhance the spatial variability of velocity distribution, resulting in an increase of exchange flux, a decrease in lag time, and an extension of the migration path. For heterogeneous media, it is easier to form specific channels for high velocity flow, and the flow velocity within them is more sensitive to changes in media and hydrodynamic conditions, the direction of hyporheic exchange can be reversed in some specific channels. For the nitrogen cycle processes, the heterogeneous medium condition determines the source-sink functions and the direction of nitrate nitrogen reduction in hyporheic zone by providing a wider reaction space for reactants, reducing the lag time to 1/40 and increasing the migration path by 4 times. The flood process can increase the infiltration amounts of reactants by 5 times and reduce the lag time (time of particle entry into the hyporheic zone to migrate out) to 1/6. In general, under the effects of media heterogeneity and flood processes, the reaction rates and nitrate nitrogen reduction rates during the nitrogen cycle processes are decreasing and the hyporheic zone will face greater pollution risks.

Numerical and experimental investigation of heat transfer across semi-transparent horizontal screen layers

Estimating the total heat flux passing through layers of materials is commonly used to determine the performance and potential of thermal isolation for general building design. The thermal properties of building glazing have been studied theoretically and experimentally for several decade. In this study, an enhanced algorithm for calculating the heat transfer through semi-transparent screens was developed and validated via published data and in-site experiments in order to analyze thermal properties of different screen materials and their combinations under more realistic conditions. The proposed algorithm allows to simplify the linearization of a nonlinear system, which is solved by inverting a tridiagonal matrix. Overall heat transfer coefficients (U-values) for single and multiple thin-screens were calculated numerically and measured using the hot-box method. The building insulating materials such as glass, polymers, aluminium films, and selected commercial thermal screens were examined. The cross-validated results indicated good agreement between calculated, measured and previously published results demonstrating the abilities of the method to predict new data for materials and their combinations that have not yet been estimated. Moreover, the algorithm allows to adopt the experimentally validated results to real ambient conditions by applying relevant scaling methods. The following results demonstrate the insulation properties of various commercial thermal screens. It is found that U-values reduce by 30% and 15% for the combination of a glass screen with an additional layer of a transparent infra-red (IR) radiation absorbing screen and a polyethylene screen, respectively. In comparison, the contributions of an additional screen containing aluminium foil strips could reduce the U-value by about 80% and 70% for polyethylene and glass cover screen, respectively. It was confirmed that low-emissivity materials have a more significant effect on reducing the U-value than insulating materials with IR-absorbing properties. The approach is valid for investigating the performance of thermal insulation in different enclosures, glazing in buildings, or moveable thermal screens in greenhouses.

Design, modeling and experimental validation of a micro cantilever beam with an electro-controllable twisting ability

The structure design of micro cantilever beams(MCBs), which has a significant effect on MCBs’ controllable actuation range, is usually restricted by the establishment of the inner electric circuit. This paper proposes the design of a micro electro-controllable twisting cantilever beam (METCB). The architecture and the fabrication diagram of the proposed METCB are presented before its features are theoretically and experimentally validated. In detail, the analytical validation includes a sequence of two models: electro-thermal and thermo-mechanical. Through these two models, the thermal distribution along the METCB and the deformation brought by the thermal distribution are investigated, respectively. On the basis of the design and equations, the METCB samples have been manufactured using a planar deposition technique with an e-beam evaporator. Two in-site experiments are then conducted to sequentially figure out the upper voltage limit of the inner electric circuit and the maximum temperature limit of the METCB. Finally, another experiment is carried out to explore the relation between the applied voltage and the relative twisting angle of the METCB sample. The theoretical prediction and the observed experiment result both prove the feasibility of the proposed METCB and its electro-controllable twisting ability.

Application of Magneto Rheological Damper System In Warren Truss Bridge Structure

This paper considers the application of magnetorheological (MR) damper, RD-8040-1, for attenuation vibration in flexible truss bridge deck structures. The modeling and identification of the damper property by using SAP2000 analysis software from an experimental data set generated by dynamic tests of the MR damper mounted in a testing machine where velocity and current are used as input, and the force as output. Theoretical investigations and in-site experiments are carried out in Chamran’s laboratory, Ahvaz, Iran. Truss bridges are an innovative structure that shall be studied in their systems and connections to earn stability and damping in related to certain lateral loads such as seismic load's post-earthquake load. The issue of damping is the cooperation between elements in the truss bridge of deck systems. Significantly, MR damper among components based on their reaction can be defined in the form of a percentage of control of loads in the structure of deck in a bridge system. This article proposes the application of damper at interconnecting of bridge deck through minimizing vibration force by using the Bouc-wen model. In summary, this paper is understood the effect of damping application on overall formation nonlinear analysis Models at this major element.

Sensitive analysis of ground recharge estimation model, for semiarid areas

The rapid demographic evolution wields a big pressure on water resources potentialities; in addition, the climate change effects have influenced the natural renovation rate of water resources around the world. Starting from a previous published model, a sensitive analysis was established after introducing three parameters as watershed topography, stream network density and geology index to illustrate the impact of each of these parameters on the rate of groundwater recharge. This modified model has been improved by in-site experiment (soil chloride mass balance) tested in some selected sites in Sidi Slimane River located in the region of Djelfa at 300 km from Algiers (Algeria). The results obtained show that the parameters like geology, topography and the amount of rainfall and the drainage density influence the velocity of groundwater recharge. By introducing the chloride concentration in soil, the model becomes most independent and gives good results that can be used in water resources planning in semiarid land.

Current Status of the KURT and Long-term In-situ Experiments

This paper reports on the current status of the KURT (KAERI Underground Research Tunnel) located in KAERI site and suggests roles of the KURT for HLW disposal in Korea. The KURT has total 551 m tunnel length, maximum 120 m depth from the surface and 6 research modules. It has been safely operated since it was constructed in November, 2006 and extended in January, 2015. Total 14 main in-site experiments were carried out and some of them are still carrying out for HLW disposal technology development and verification of feasibility, stability and safety of the main components of disposal system. Especially, In-DEBS (In-Situ Demonstration of Engineered Barrier System) is the first in-situ experiment of EBS performance in Korea and its designing, manufacturing and installing were carried out by domestics technology. The KURT will play an important role in development of disposal technologies and their assessments, and in expert training and the public confidence building for the disposal technologies.

In-site experiments on the swelling characteristics of a shield tunnel in expansive clay: A case study

Expansive soil swells, softens, and disintegrates when absorbing water, whereas it shrinks when losing water. Understanding the swelling characteristics of a shield tunnel in expansive soil is important. However, most in-site experiences on the swelling characteristics of a tunnel are obtained from the NATM tunnels constructed in swelling rock using drill and blast method; most laboratory experiments or theoretical analyses on the swelling characteristics of a shield tunnel in expansive soil are under certain hypotheses which have not been verified in actual situation. To solve the problems, the Slender West Lake tunnel was selected as the background, laboratory and in-site experiments were performed to understand the swelling characteristics of a shield tunnel in expansive clay. Four experimental sections were constructed in the actual tunnel. The measuring gauges were pre-installed in the segments in factory and the segments were installed in-site to observe the actual earth pressure and temperature during construction. The influences of expansive soil to the distributions and variations of earth pressure, bending moment, and temperature were analyzed. The increasing earth pressure was divided into three stages. Large earth pressure was detected at the top, bottom, left, and right sides of the tunnel. The earth pressure at the left and right sides was larger than that at the top and bottom. Large negative bending moment was detected at the top and bottom of the tunnel, whereas large positive bending moment was detected at the left and right sides of the tunnel. The minimum bending moment appeared at 45° oblique. The largest negative bending moment was larger than the largest positive bending moment. Based on the observations, a load mode of swelling pressure for a beam-spring model was suggested. It can be referred by the similar tunnels.

Fatigue Life Evaluation For Wind Turbine Blade Based on Multistage Loading Accumulative Damage Theory

The fatigue life of MW wind turbine blade was assessed by applying theoretical calculation and test verification. Firstly, the fatigue characteristic curve of FRP material was obtained based on Palmgren-Miner damage theory. Furthermore, The fatigue life of Aeroblade1.5-40.3 wind turbine blade using multistage loading accumulative damage theory could be evaluated over 20 years accordingly. Then the coordinate system of wind turbine blade and its Bladed simulation model were set. By calculating fatigue loading, the moment distribution of fatigue test was obtained. Finally, the blade’s fatigue loading system driven by an eccentric mass was built and the multi-level amplitude resonant mode was adopted to carry on the test. Almost three months’ test results showed that the blade vibrating amplitude was constant, which illustrate the little variation of stiffness of loading point. The stable of stiffness could testify the fatigue life of blade was over 20 years. The results of in-site experiment were basically consistent with the theoretical calculation.

Construction of Plant Communities for Ecological River Training and their Impacts on Biological Diversity

River play a very important role in regional landscape structure as an ecological element and corridor, and vegetation is very important for the healthy eco-system of a river. The advances of the research and application of near nature river training and vegetation measures were reviewed. The concept, content and function of ecological river training and near natural river training were discussed.. According to the principle of landscape biology, the positive influence of river vegetation on biodiversity was analyzed through edge effects, corridor effects and interference effects. On the basis of in-site experiments of more then ten sample rivers for years, it was concluded that to meet the needs of biodiversity conservation and maintain river ecosystem healthy and steady, in the design and construction of a river, the ecological function should take into due account, proper habitat conditions for plants and plant communities should be created through suitable plan layout, cross section, slope structure and construction material.

Analysis for Axial Vibration and Internal Forces of Totally and Partially Embedded Pile Groups with Flexible Caps

In this paper, a simplified analytical method is developed for the axial harmonic response of totally and partially embedded pile groups in homogeneous and layered soil deposits. Based on BDWF model, finite element sub-structure method is used to setup the dynamic model of cap-pile groups which can precisely simulate kinetic interaction and inertial interaction. A comprehensive parameter study focuses on the influence of caps’ elastic modulus and mass density on pile groups’ dynamic response, and then points out the limition of rigid cap in practical design. An approximate solution is finally presented for the internal forces distributed on pile heads due to pile-to-pile interaction. The solution of above approach was compared with that of traditional simplified model (rigid and massless cap solution) in simulating an in-site experiment and dynamics response of partially embedded pile groups for offshore wind farm.