Good Agreement Research Articles

Efficient homogenization of honeycomb sandwich panels using orthotropic core simplification and Finite Element-based method: A comparative study

Composite materials, particularly honeycomb composites, are widely utilized in various industries, including aerospace, due to their high energy absorption against the impact and exceptional strength-to-weight ratio. This study aims to leverage the plastic and elastic properties of these materials to develop a simplified numerical model that incorporates orthotropic properties for core modeling. By doing so, the need for detailed honeycomb structure modeling is eliminated, resulting in reduced computational costs and time. A comprehensive three-dimensional finite element model, accounting for structural intricacies, is presented based on experimental data from a reputable source (isotropic model) and its equivalent finite element model (orthotropic model). The model is validated by the experimental results, demonstrating good agreement. The study also investigates parameters such as energy absorption, the internal energy of the core and faces, maximum displacement, and maximum contact force under low-velocity impact scenarios with spherical and cylindrical projectiles. These findings highlight the effectiveness of the orthotropic model, particularly in showcasing greater energy absorption in the core of the sandwich panel when subjected to a cylindrical impactor.

Phase field modelling and simulation of damage occurring in human vertebra after screws fixation procedure

AbstractThe present endeavour numerically exploits the use of a phase-field model to simulate and investigate fracture patterns, deformation mechanisms, damage, and mechanical responses in a human vertebra after the incision of pedicle screws under compressive regimes. Moreover, the proposed phase field framework can elucidate scenarios where different damage patterns, such as crack nucleation sites and crack trajectories, play a role after the spine fusion procedure, considering several simulated physiological movements of the vertebral body. Spatially heterogeneous elastic properties and phase field parameters have been computationally derived from bone density estimation. A convergence analysis has been conducted for the vertebra-screws model, considering several mesh refinements, which has demonstrated good agreement with the existing literature on this topic. Consequently, by assuming different angles for the insertion of the pedicle screws and taking into account a few vertebral motion loading regimes, a plethora of numerical results characterizing the damage occurring within the vertebral model has been derived. Overall, the phase field results confirm and enrich the current literature, shed light on the medical community, which will be useful in enhancing clinical interventions and reducing post-surgery bone failure and screw loosening. The proposed computational approach also investigates the effects in terms of fracture and mechanical behaviour of the vertebral-screws body within different metastatic lesions opening towards major life threatening scenarios.

Experimental Study on Physical and Mechanical Properties of Lightweight Cellular Concrete Specimens Cast in Field and Laboratory

This paper presents a series of laboratory tests for evaluating the material properties of Lightweight cellular concrete (LCC) with different cement-to-fly ash ratios and at different ages. LCC specimens used in this study were cast in the field and/or laboratory. Large and small direct shear box tests were used to determine the shear strengths of LCC specimens. The test results show that the average wet densities for the LCC specimens cast in the laboratory ranged from 460 to 491 kg/m3, whereas the average wet densities for the specimens cast in the field ranged from 480 to 578 kg/m3 at the age of 28 days. The permeability values for the LCC specimens cast in the field ranged from 5.4 × 10-7 to 7.7 × 10-6 m/s and the permeability values for the LCC specimens cast in the laboratory ranged from 6.8 × 10-7 to 2.5 × 10-6 m/s. The measured peak friction angles of the LCC specimens from the small direct shear box tests ranged from 19° to 63°, whereas the measured peak friction angles of the LCC specimens from large direct shear box tests ranged from 23° to 79°. The average measured compressive strengths for the LCC specimens cast in the field and laboratory ranged from 0.43 to 1.15 MPa and 1.08 to 1.11 MPa at the age of 28 days, respectively. LCC specimens showed shrinkage behavior when subjected to wet–dry cycles and had good resistance to freeze–thaw cycles following ASTM D560/560M. The paper also compares the material properties of LCC measured in this study with those reported in the literature and the comparison shows good agreement overall.

Validation of a Model Estimating the Budget Impact of Video Capsule Endoscopy for Surveillance of Crohn’s Disease in an Italian Center

Background: Crohn’s disease is a chronic ailment affecting the gastrointestinal tract. Mucosal healing, a marker of reduced disease activity, is currently assessed in the colonic sections using ileocolonoscopy and magnetic resonance enteroscopy. Video capsule endoscopy (VCE) offers visualization of the entire GI mucosae. Objective: To validate a Crohn’s disease model estimating the budget impact of VCE compared with the standard of care (SOC) in Italy. Methods: A patient-level, discrete-event simulation was developed to estimate the budget impact of VCE compared with SOC for Crohn’s disease surveillance over 5 years in the Italian setting. Input data were sourced from a physician-initiated study from Sant’Orsola-Malpighi Hospital in Bologna, Italy, and the literature. The care pathway followed hospital clinical practice. Comparators were the current SOC (ileocolonoscopy, with or without magnetic resonance enteroscopy) and VCE. Sensitivity analysis was performed using 500-patient bootstraps. A comparative analysis regarding clinical outcomes (biologics use, surgical interventions, symptom remission) was performed to explore the validity of the model compared with real-world data. Cumulative event incidences were compared annually and semi-annually. Bayesian statistical analysis further validated the model. Results: Implementing VCE yielded an estimated €67 savings per patient per year, with savings in over 55% of patients, compared with SOC. While annual costs are higher up to the second year, VCE becomes cost saving from the third year onward. The real-world validation analysis proved a good agreement between the model and real-world patient records. The highest agreement was found for biologics, where Bayesian analysis estimated an 80.4% probability (95% CI: 72.2%-87.5%) that a decision maker would accept the result as an actual reflection of real-world data. Even where trend data diverged (eg, for surgery [43.1% likelihood of acceptance, 95% CI: 33.7%-52.8%]), the cumulative surgery count over 5 years was within the margin of error of the real-world data. Conclusions: Implementing VCE in the surveillance of patients with Crohn’s disease and small bowel involvement may be cost saving in Italy. The congruence between model predictions and real-world patient records supports using this discrete-event simulation to inform healthcare decisions.

Validation of a Model Estimating the Budget Impact of Video Capsule Endoscopy for Surveillance of Crohn's Disease in an Italian Center.

Background: Crohn's disease is a chronic ailment affecting the gastrointestinal tract. Mucosal healing, a marker of reduced disease activity, is currently assessed in the colonic sections using ileocolonoscopy and magnetic resonance enteroscopy. Video capsule endoscopy (VCE) offers visualization of the entire GI mucosae. Objective: To validate a Crohn's disease model estimating the budget impact of VCE compared with the standard of care (SOC) in Italy. Methods: A patient-level, discrete-event simulation was developed to estimate the budget impact of VCE compared with SOC for Crohn's disease surveillance over 5 years in the Italian setting. Input data were sourced from a physician-initiated study from Sant'Orsola-Malpighi Hospital in Bologna, Italy, and the literature. The care pathway followed hospital clinical practice. Comparators were the current SOC (ileocolonoscopy, with or without magnetic resonance enteroscopy) and VCE. Sensitivity analysis was performed using 500-patient bootstraps. A comparative analysis regarding clinical outcomes (biologics use, surgical interventions, symptom remission) was performed to explore the validity of the model compared with real-world data. Cumulative event incidences were compared annually and semi-annually. Bayesian statistical analysis further validated the model. Results: Implementing VCE yielded an estimated €67 savings per patient per year, with savings in over 55% of patients, compared with SOC. While annual costs are higher up to the second year, VCE becomes cost saving from the third year onward. The real-world validation analysis proved a good agreement between the model and real-world patient records. The highest agreement was found for biologics, where Bayesian analysis estimated an 80.4% probability (95% CI: 72.2%-87.5%) that a decision maker would accept the result as an actual reflection of real-world data. Even where trend data diverged (eg, for surgery [43.1% likelihood of acceptance, 95% CI: 33.7%-52.8%]), the cumulative surgery count over 5 years was within the margin of error of the real-world data. Conclusions: Implementing VCE in the surveillance of patients with Crohn's disease and small bowel involvement may be cost saving in Italy. The congruence between model predictions and real-world patient records supports using this discrete-event simulation to inform healthcare decisions.

The distance to CRL 618 through its radio expansion parallax

ABSTRACT CRL 618 is a post-Asymptotic Giant Branch star that has started to ionize its ejecta. Its central H ii region has been observed over the last 40 yr and has steadily increased in flux density at radio wavelengths. In this paper, we present data that we obtained with the Very Large Array in its highest frequency band (43 GHz) in 2011 and compare these with archival data in the same frequency band from 1998. By applying the so-called expansion-parallax method, we are able to estimate an expansion rate of 4.0 ± 0.4 mas yr−1 along the major axis of the nebula and derive a distance of 1.1 ± 0.2 kpc. Within errors, this distance estimation is in good agreement with the value of ∼900 pc derived from the expansion of the optical lobes.

High energy gamma-ray sources in the VVV survey - II. The AGN counterparts

ABSTRACT We identified Active Galactic Nuclei (AGN) candidates as counterparts to unidentified gamma-ray sources (UGS) from the Fermi-LAT Fourth Source Catalogue at lower Galactic latitudes. Our methodology is based on the use of near- and mid-infrared photometric data from the VISTA Variables in the Vía Láctea (VVV) and Wide-field Infrared Survey Explorer (WISE) surveys. The AGN candidates associated with the UGS occupy very different regions from the stars and extragalactic sources in the colour space defined by the VVV and WISE infrared colours. We found 27 near-infrared AGN candidates possibly associated with 14 Fermi-LAT sources using the VVV survey. We also found 2 blazar candidates in the regions of 2 Fermi-LAT sources using WISE data. There is no match between VVV and WISE candidates. We have also examined the Ks light curves of the VVV candidates and applied the fractional variability amplitude (σrms) and the slope of variation in the Ks passband to characterise the near-infrared variability. This analysis shows that more than 85 per cent of the candidates have slopes in the Ks passband >10−4 mag/day and present σrms values consistent with a moderate variability. This is in good agreement with typical results seen from type-1 AGN. The combination of YJHKs colours and Ks variability criteria was useful for AGN selection, including its use in identifying counterparts to Fermi γ-ray sources.

Coupled Vibration Analysis of Multi-Span Continuous Cable Structure Considering Frictional Slip

As important load-bearing structures, suspension cables have been widely used in suspension bridges, engineering ropeways, cable suspension systems and other special equipment. Their dynamic problems have always been a research hotspot. Especially for complex cable systems such as engineering ropeways and cable lifting equipment, there will be moving loads acting on multi-span continuous friction-slip cable structures, resulting in nonlinear coupled vibration. Therefore, few scholars have studied how to calculate the nonlinear coupling vibration effect between such moving loads and multi-span continuous cables considering friction slip. Therefore, this paper proposes the use of the combination of the direct stiffness method and the Newmark-β integration method to solve the nonlinear system of equations of motion, which can be derived from the coupled vibration response between the moving load and the main cable. The corresponding calculation program is prepared. Combined with the dynamic load test and simulation results of engineering cases, the correctness and reasonableness of the coupled vibration equations and the program can be verified through comparative analysis. The results show that the calculation results of the self-programmed program are in good agreement with the dynamic load test results, in which the maximum error of the vertical displacement in the span is −4.40% and 0.86%, and the error of the static calculation reaches −13.90%. The impact effect is more obvious when hoisting the weight out of the pulling cable, in which the impact coefficient of the main cable can be up to 2.0. The impact coefficient of the deviation of the cable tower is 4.0. During the traveling process of the moving load, the vertical downward deflection of the main cable at the action point is the largest, and the upward deflection is in the region of 0.2~0.8L from the action point.

Virtual laboratory enabled constitutive modelling of dual phase steels

Accurate and efficient characterization and modelling of deformation responses are critically essential in the development of advanced metal forming processes. This work presents a virtual laboratory enabled constitutive framework for modelling complex deformation responses of dual phase (DP) steels under complex stress states, based on multi-phase full-field crystal plasticity (CP) and advanced phenomenological modelling. In the CP based virtual testing method, kinematic hardening and degradation of elastic modulus are modelled in particular to improve the capability for describing evolving microstructure induced mechanical responses of DP steels. The workflow of this framework is completely built and numerically implemented, including (i) representative volume element (RVE) generation based on microstructure characterization, (ii) identification of multiphase CP model parameters, (iii) prediction of elastic modulus degradation, (iv) prediction of yield stresses and plastic potentials in uniaxial tension and biaxial tension with various stress ratios, and (v) prediction of stress–strain curves in reverse tension compression. Using DP780 and DP980 as case materials, the corresponding physical experiments are conducted to verify the accuracy of the virtual tests, showing a good agreement between the virtual and experimental approaches. Both experimental and virtual tests are used to calibrate advanced phenomenological constitutive models that include non-linear elasticity, anisotropic yielding, and kinematic hardening. The calibrated models are implemented into the finite element (FE) codes to predict complex deformation and springback behaviours of DP780 and DP980 sheets in U-bending processes. In comparison with forming experiments of U-channel parts, the virtually calibrated models are validated and show good performance in predicting deformation and springback behaviours, providing a high capability for process analysis. The findings support that the virtual laboratory enabled modelling approach could be a substitute for extensive, expensive, and hard-to-access physically mechanical experiments required in the model calibration for a more effective and efficient analysis of metal forming processes.

Bio-Interface Analysis and Detection of Aβ using GaN HEMT-based Biosensor

Early detection, prognosis, and diagnosis of devastating neurological disorders such as TBI and AD are crucial for developing treatment strategies, efficient patient outcomes, and management in biomedical fields. The work reports the design, development, suitability analysis, and validation of a label-free GaN HEMT-based biosensing platform for the non-invasive detection of FDA-approved biomarker Aβ in saliva sample concentration ranges. The biofunctionalization assay has been validated with both electrical and FTIR spectroscopy-based measurements. A comparative analysis with ELISA assay shows good agreement with ∼2.0% measurement errors demonstrating platform stability and accuracy for Aβ detection. The platform offers a peak sensitivity of 27.20 μA/pg ml−1, 19.10 μA pg−1 ml−1, and 1.48 μA/pg ml−1 for detection in saliva, serum, and CSF concentration ranges with high specificity, excellent repeatability, and reproducibility of the results. The platform offers a sensitivity of 2.40 μA/pg ml−1, 15.40 μA pg−1 ml−1, and 27.20 μA/pg ml−1 for Sbias of 1.0 V, 3.3 V, and 5.0 V respectively. The key biosensor features include fast detection with a response time of 5–10 s and a low sample volume requirement of ∼1–2 μl. The platform comparison with ELISA shows a similar and acceptable linearity trend. A novel equation has been established for ELISA and developed platform-based detection for possible detection accuracy and validation useful for correlating the sensor response with ELISA test results and vice-versa for any target Aβ concentrations. To the best of our knowledge, this is the first time reporting of Aβ detection using a GaN HEMT-based biosensing platform.

The PAU Survey: a new constraint on galaxy formation models using the observed colour redshift relation

Abstract We use the GALFORM semi-analytical galaxy formation model implemented in the Planck Millennium N-body simulation to build a mock galaxy catalogue on an observer’s past lightcone. The mass resolution of this N-body simulation is almost an order of magnitude better than in previous simulations used for this purpose, allowing us to probe fainter galaxies and hence build a more complete mock catalogue at low redshifts. The high time cadence of the simulation outputs allows us to make improved calculations of galaxy properties and positions in the mock. We test the predictions of the mock against the Physics of the Accelerating Universe Survey, a narrow band imaging survey with highly accurate and precise photometric redshifts, which probes the galaxy population over a lookback time of 8 billion years. We compare the model against the observed number counts, redshift distribution and evolution of the observed colours and find good agreement; these statistics avoid the need for model-dependent processing of the observations. The model produces red and blue populations that have similar median colours to the observations. However, the bimodality of galaxy colours in the model is stronger than in the observations. This bimodality is reduced on including a simple model for errors in the GALFORM photometry. We examine how the model predictions for the observed galaxy colours change when perturbing key model parameters. This exercise shows that the median colours and relative abundance of red and blue galaxies provide constraints on the strength of the feedback driven by supernovae used in the model.

Optical Bubble Microflow Meter for Continuous Measurements in a Closed System

This paper describes the design, operation and test results of a simple microprocessor-based device for measuring slow liquid flows. The device uses a module of 30 digital optical sensors to track the movement of a single air bubble inserted into a tube of flowing liquid. During a measurement session, the air bubble remains within the sensor module at all times, allowing the instrument to take measurements for any length of time. The liquid whose flow rate is being measured moves only in the closed tube system, without contact with other components of the device. The test of the device itself was carried out using a tube with an inner diameter of less than 1 mm, where the device is capable of measuring flow rates on the order of microliters per minute. Tests of the device showed good agreement between the measured volumetric flow rate and the reference flow rates of the infusion pump over the entire measurement range. The advantages and limitations of the device are discussed, as well as the prospects for developing the method.

Study on enhancing waste PVC management through predictive Machine Learning analysis of TGA and its economic benefits

The onset of COVID-19 has led to a sudden surge of existing medical plastic wastes, majority of them made up of PVCs. Pyrolysis, a globally adopted waste management alternative, can be a crucial aid to handle the bulk plastic wastes which makes the identification of thermal behaviour of materials important to aid in the scale-up of pyrolytic processes. The study presents a novel approach of utilising regression-based algorithms- Support Vector Regression (SVR), Random Forest Regression (RFR) and K-Nearest Neighbour algorithms (KNN), to predict the weight loss % at a heating rate of 20 K/min for 6 different PVC based medical plastic wastes. The correlation between the factors affecting Thermogravimetric Analysis (TGA) have been identified using heat maps, the Machine Learning (ML) models were trained on this TGA data and the model efficiencies were identified using performance metrics of Mean Squared Error (MSE), Mean Absolute Error (MAE) and R2. Several kinetic parameters like activation energy and reaction order were estimated using Coats - Redfern method followed by a cost analysis. The results showed that experimental and predicted weight loss were in good agreement with a regression R2 value > 0.97 for all the materials except the composite outer cover. Coats - Redfern method was successful in the estimation of kinetic parameters and the economic analysis indicated that the utilisation of ML in TGA analysis can have significant financial benefits for the concerned industry.

Effects of MHD and thermal radiation on non-Newtonian fluid with Cattaneo–Christov heat over a stretching flow surface

In this study, we are investigating the flow of an incompressible Williamson fluid using a Cattaneo–Christov heat flux model, with consideration for a magnetic Reynolds number that is not high. This fluid flows over a linearly stretched 2-D surface and is affected by a magnetic field, thermal radiation-diffusion, and heat generation. To model the Williamson flow, we apply a boundary layer approximation and develop the ordinary differential equations. The system of differential equations is transformed into a system of ordinary differential equations using a suitable transformation. We utilize the Iterative Runge–Kutta fourth-order scheme to numerically solve the boundary conditions associated with the nonlinear, dimensionless ordinary differential equations. Graphical representations of the results are employed to analyze the impact of physical properties on velocity, temperature, and concentration, with the numerical results presented in tabular form. Upon comparing our findings with previously published results, we have found them to be in good agreement. The velocity decreases as the Williamson fluid factor gradually increases. Williamson fluids are recognized for their shear thinning behavior, wherein viscosity decreases as the shear rate increases. However, higher parameter values can lead to increased fluid viscosity, potentially reducing the degree of shear thinning. This phenomenon results in a more uniform viscosity profile across varying shear rates, contributing to a reduced velocity distribution within the fluid.

Continuous GHz femtosecond laser interacting with aluminum film: Simulation and experiment

GHz femtosecond laser has attracted more research interest due to the so-called high-efficiency cold ablation effect. In this study, behavior of continuous GHz (cGHz), i.e., GHz repetition frequency femtosecond laser with no burst mode, interacting with aluminum (Al) film has been investigated numerically and experimentally. For this purpose, an axisymmetric two-temperature model was used, accounting for the thermodynamical evolution of Al film. Laser irradiating Al film experiments were also carried out simultaneously. The calculated temperature field evolution was in good agreement with the observed experimental results. Effects of laser fluence and scanning speed on morphology, area, height, and volume of the residual Al film were then sequentially studied. Interestingly to see, for this cGHz femtosecond laser source, melting and re-solidification lead to the material removal under low laser fluence, say, ≤0.0337 J/cm2 in this study. For the whole Al film, with laser fluence increasing, the outmost lattice evaporation and beneath lattice melting occur together, both responsible for material removal and morphology variation. Finally, a potentially beneficial GHz femtosecond laser mode for high-quality microfabrication is proposed.

Using radial basis function for estimating the high-performance concrete compressive strength with optimizing AVOA and SSA

Compressive strength (CS) is concrete’s most important mechanical property, as it plays an important role in setting design criteria. Thus, an accurate and early assessment of the CS of concrete can minimize time, labor, and cost. This paper investigated the ability of the Radial Basis Function (RBF) to handle the prediction of CS. The nonlinearities raised from the novel utilized admixtures between the input variables and output CS is tried to be conducted with the RBF model. In order to make a flexible framework combination of the RBF model with the African Vulture Optimization (AVOA) and Salp Swarm Algorithm (SSA) techniques are considered. The results achieved from the RBF-AVOA model indicated good agreement between the actual and predicted values. The proposed model provides a very accurate HPC compressive strength prediction. In addition, the correlation coefficient R2 is equal to (0.997), and the values of mean absolute error (MAE) (0.1917 MPa), root mean square error (RMSE) (0.937 MPa), and variance account coefficient (VAF) (99.73%) are low. The performance of the RBF-AVOA model, compared to other models, provided the desired advantage and more stable predictions. AVOA plays a key role in modeling results, improving generalization capabilities, avoiding redundant data, and decreasing uncertainty.

Corrosion Inhibition of Expired Cefazolin Drug on Copper Metal in Dilute Hydrochloric Acid Solution: Practical and Theoretical Approaches.

In this work, we studied the corrosion of Cu metal in 0.5 mol L-1 HCl and the inhibition effect of the expired Cefazolin drug. The inhibition efficiency (IE) of Cefazolin varied according to its concentration in solution. As the Cefazolin concentration increased to 300 ppm, the IE increased to 87% at 298 K and decreased to 78% as the temperature increased to 318 K. The expired drug functioned as a mixed-type inhibitor. The adsorption of the drug on the copper surface followed Temkin's adsorption model. The magnitudes of the standard free energy change (ΔGoads) and adsorption equilibrium constant (Kads) indicated the spontaneous nature and exothermicity of the adsorption process. Energy dispersive X-ray (EDX) and scanning electron microscopy (SEM) techniques showed that the drug molecules were strongly attached to the Cu surface. The electrochemical frequency modulation (EFM), potentiodynamic polarization (PP), and electrochemical impedance spectroscopy (EIS) results were in good agreement with the results of the weight loss (WL) method. The density functional tight-binding (DFTB) and Monte Carlo (MC) simulation results indicated that the expired drug bound to the copper surface through the lone pair of electrons of the heteroatoms as well as the π-electrons of the tetrazole ring. The adsorption energy between the drug and copper metal was -459.38 kJ mol-1.

Finite Element Simulation Parameter Calibration and Verification for Stem Cutting of Hydroponic Chinese Kale

The finite element simulation is a valid way for the rapid development of the root-cutting mechanism for hydroponic Chinese kale. The stem of the hydroponic Chinese kale was simplified as a transverse isotropic elastic body, and axial compression, three-point bending, and shear tests were performed. The ANSYS/LS-DYNA19.2 software was adopted for stem shear simulation, and the regression equation of the maximum simulated shear force was established. The optimized mechanical parameters were determined by minimizing the deviation between the maximum shear force obtained from the simulation and test. The three-dimensional scanning method was employed to establish the geometric model of the hydroponic Chinese kale stem. The cutting finite element simulation model and test platform were constructed. Displacement, deformation, and force measured from simulation and test were compared. Through measurement and simulation calibration, an axial elastic modulus of 6.22 MPa, axial Poisson’s ratio of 0.46, radial elastic modulus of 3.56 MPa, radial Poisson’s ratio of 0.44, radial shear modulus of 0.8 MPa, and a failure strain of 0.08 were determined. During the cutting simulation and test, the resulting maximum displacement deviations of the marking points on the end of the stem were 0.68 mm along the X-axis and 2.83 mm along the Y-axis, while the maximum deviations of the cutting and clamping force were 0.49 N and 0.77 N, respectively. The deformation and force variation laws of the kale stem in the cutting simulation and test process were basically consistent. It showed that the mechanical parameters calibrated by the simulation were accurate and effective, and the stem cutting simulation results with the finite element method were in good agreement with that of the cutting test. The study provided a reference for the rapid optimization design of the root-cutting mechanism for hydroponic Chinese kale harvest.

Application of integrated geophysical techniques in geothermal exploration in Binhai County, Jiangsu Province

AbstractIntegrated geophysical technology is a necessary and effective means for geothermal exploration. However, integration of geophysical technology for large‐scale surveys with those for geothermal reservoir localization is still in development. This study used the controlled source audio‐frequency magnetotelluric method technology for large‐scale exploration to obtain underground electrical structure information and micromotion detection technology to obtain underground wave velocity structure information. The combination of two detection technologies was used for local identification of geothermal reservoirs. Further, auxiliary correction and inversion constraint were implemented through the audio magnetotelluric sounding technology for maximum authenticity restoration of the near‐ and transition‐field data. Through these technology improvements, a geothermal geological model was established for the Binhai County of Jiangsu Province in China and potential geothermal well locations were identified. On this basis, a geothermal well was drilled nearly 3000 m deep, with a daily water volume of over 2000 m3/day and a geothermal water temperature of 51°C at the well head. It is found that predictions using the above integrated geophysical exploration technology are in good agreement with the well geological formation data. This integrated geophysical technology can be effectively applied for geothermal exploration with high precision and reliability.

THERMOREGULATION SYSTEM FOR BIOSENSORS BASED ON FIELD-EFFECT TRANSISTORS WITH A NANOWIRE CHANNEL

In this work we present an automatic thermoregulation system for biosensors based on field-effect transistors with a nanowire channel, which provides full control on the required temperature regime in bioanalytical analises. The system elements, including field-effect transistors with a nanowire channel, temperature sensors and heaters, were fabricated on a single silicon cristal using electron beam lithography, reactive ion etching and high-vacuum deposition techniques. Unicue electronics have been developed to control and maintain temperature. The dependence of thermometer readout on heating power was measured, which is in good agreement with the results of numerical simulation. A demonstration of a thermoregulation system with PID-feedback was carried out, ensuring the establishment of a desiered temperature in the range of 30-70◦ C in 18 s in liquid. A demonstration of a thermoregulation system for detecting nucleic acids was carried out using synthetic single-stranded DNA, which is a gene fragment from the bacterium Escherichia coli. The minimal detectable response was observed for a sample with a concentration of 3 fM.