Three-dimensional Response Research Articles

Optimization of ultrasonic-assisted extraction of phenolic compounds and antioxidant activities From Pistacia atlantica Desf. galls using response surface methodology

In the present study, the response surface methodology (RSM) using Box-Behnken design (BBD) was employed to optimize conditions for the extraction of phenolic compounds from Pistacia atlantica Desf. leaf galls. Three variables were evaluated at three levels (15 experimental runs): the extraction time (40 min, 45 min, and 50 min), the solid-to-liquid ratio (1:10 g/ml, 1: 20 g/ml, and 1:30 g/ml) and temperature (40 °C, 50 °C, and 60 °C). According to the three-dimensional response surface, the optimum extraction phenolic compounds were found at 40 min extraction time, 1:20 g/ml solid-liquid ratio, and 60 °C extraction temperature. In these conditions, the content of TPC, TFC, CTC, and antioxidant activity (DPPH and iron chelation) were 139.88 mg GAE/g DW, 2.43 mg QE/g DW, 121.32 mg CE/g DW, 65.94 mg AAE/g DW, and 501.38 mg TE/g DW, respectively. The results indicate an agreement between the prediction values and experimental ones, which points the success of the optimization. Moreover, they indicate that P. atlantica galls produce a high amount of antioxidants and antiradicals under optimized conditions determined by RSM. Actually, the used method is a simple, reliable one that serves as an alternative to various other extraction techniques.

Three-dimensional nonlinear stability analysis of axial-thermal-electrical loaded FG piezoelectric microshells via MKM strain gradient formulations

The present study focuses on the moving Kriging meshfree (MKM) technique combined with the three-dimensional strain gradient continuum mechanics to analyze three-dimensional nonlinear stability response of thermo-electro-mechanical loaded functionally graded (FG) piezoelectric cylindrical microshells. The derived three-dimensional MKM model has the capability to present the transition of buckling mode containing different microsize-dependent gradient tensors. The microshells are made of a mixture containing PZT-4 and PZT-5H piezoelectric phases, the material properties of which vary continuously along the shell thickness and captured based on the power law composition scheme. With the aid of MKM strain gradient-based shell model, it is possible to satisfy the function property associated with Kronecker delta by putting the required boundary conditions directly at the associated nodes without any predefined mesh. The microsize-dependent nonlinear stability plots are obtained in the presence of modal transition relevant to various environment temperatures, external electric voltages, microstructural size dependency tensors, and power-law indexes. It is found that the stiffening character related to all three microstructural strain gradient tensors is more significant for the second nonlinear stability mechanical/electrical load in comparison with the first one. However, for the three-dimensional mechanical/electrical bifurcation load, the stiffening character of these gradient tensors becomes even lower than the first postbuckling load. Moreover, by applying an actuation via a positive voltage, the first three-dimensional critical buckling load and the associated end shortening reduce, while an actuation via a negative voltage results in to increase them. It is observed that by shifting to the postbuckling territory, the role of the electric actuation gets negligible.

Viscoelastic damage evaluation of the axon.

In this manuscript, we have studied the microstructure of the axonal cytoskeleton and adopted a bottom-up approach to evaluate the mechanical responses of axons. The cytoskeleton of the axon includes the microtubules (MT), Tau proteins (Tau), neurofilaments (NF), and microfilaments (MF). Although most of the rigidity of the axons is due to the MT, the viscoelastic response of axons comes from the Tau. Early studies have shown that NF and MF do not provide significant elasticity to the overall response of axons. Therefore, the most critical aspect of the mechanical response of axons is the microstructural topology of how MT and Tau are connected and construct the cross-linked network. Using a scanning electron microscope (SEM), the cross-sectional view of the axons revealed that the MTs are organized in a hexagonal array and cross-linked by Tau. Therefore, we have developed a hexagonal Representative Volume Element (RVE) of the axonal microstructure with MT and Tau as fibers. The matrix of the RVE is modeled by considering a combined effect of NF and MF. A parametric study is done by varying fiber geometric and mechanical properties. The Young’s modulus and spacing of MT are varied between 1.5 and 1.9 GPa and 20–38 nm, respectively. Tau is modeled as a 3-parameter General Maxwell viscoelastic material. The failure strains for MT and Tau are taken to be 50 and 40%, respectively. A total of 4 RVEs are prepared for finite element analysis, and six loading cases are inspected to quantify the three-dimensional (3D) viscoelastic relaxation response. The volume-averaged stress and strain are then used to fit the relaxation Prony series. Next, we imposed varying strain rates (between 10/sec to 50/sec) on the RVE and analyzed the axonal failure process. We have observed that the 40% failure strain of Tau is achieved in all strain rates before the MT reaches its failure strain of 50%. The corresponding axonal failure strain and stress vary between 6 and 11% and 5–19.8 MPa, respectively. This study can be used to model macroscale axonal aggregate typical of the white matter region of the brain tissue.

Optimization of process parameters for electromagnetic induction heating assisted extrusion of magnesium alloy AZ91D internal thread

The forming of magnesium alloy AZ91D internal thread by electromagnetic induction heating assisted extrusion is a new processing method. In this work, on the basis of this process, the torque in the forming process is selected as the evaluation index, and the response surface method is used to analyze the influence of the process parameters on the internal thread forming process. The range of process parameters (auxiliary heating temperature, hole diameter, machine tool speed) is determined by slip line and empirical method, the test data are simulated, modeled and compared with the response surface analysis method, and the best mathematical model is selected to establish the regression model. the three-dimensional response surface curve of torque is obtained. Through simulation and prediction, it is found that the hole diameter and auxiliary heating temperature have significant influence on the torque in the forming process, and the order is that the hole diameter is larger than the auxiliary heating temperature than the machine tool speed. At the same time, it is found that the interaction between the auxiliary heating temperature and the machine tool speed has a significant effect on the torque. The research results show that the measured value of torque is close to the predicted value, and the predicted value is 3.1% lower than the actual value, and the model fits well. The better forming process parameters are as follows: auxiliary heating temperature to be 240°C, hole diameter to be 11.45 mm, machine tool speed to be 100 r/min. under this parameter, the torque in the forming process to be 24.751 N·m.

Research on anchor damage and protection of three-core composite submarine cable considering impact angle

Submarine cables are important equipment in many power engineering and communication engineering projects. However, power transmission and signal transmission is threatened by anchors hitting submarine cables. Due to the nature of the helical structure of the cable, different angles of impact have different effects on submarine cable damage. In this paper, a three-dimensional dynamic response analysis model, “ship anchor – three-core composite submarine cable – soil”, is developed based on ABAQUS to study how the impact angle of ship anchors influences the damage to submarine cables. It explores the damage to cables struck by anchors of different weights and at different speeds. The longitudinal compression rates of conductors and the optical fibre units of submarine cables at different burial depths are obtained and advice for the protection of cables is provided. The results show that anchor speed has a greater impact on cable damage than anchor mass. The impact angle on cable conductors and the optical fibre units decreases as the depth of burial increases. A burial depth greater than 1.9 times the cable diameter provides a protective effect on the submarine cable.

Finite plate elements with variable kinematics based on sublaminate generalized unified formulation

The Sublaminate Generalized Unified Formulation (SGUF) is extended for the first time to the framework of Finite Element Method (FEM) for both displacement-based and mixed (RMVT) formulation. The variable kinematics approach allows to choose different plate models according to the desired level of accuracy. Furthermore, the mixed ESL/LW approach of SGUF makes the model particularly convenient for sandwich structures analysis. A substitute interpolation for the first-order transverse shear strain field, referred to as QC4 interpolation, makes the developed four-node FE locking free and insensitive to mesh distortion. The complete expression of finite element matrices for the PVD-based and RMVT-based elements is provided. The possibility of exactly satisfying transverse stress boundary conditions for RMVT-based elements is also investigated for the first time. The flexibility and accuracy of the computational approach is demonstrated on linear static problems of sandwich plates and beams ranging from global bending response to local indentation problems. In particular, it is demonstrated that the proposed approach is capable of recovering full three-dimensional response with a 2D FE mesh and with less degrees of freedom than the conventional models available in commercial FE packages.

Three-dimensional forward calculation of time domain electromagnetic response stimulated by a pseudo-Gaussian pulse source

The calculation of three-dimensional (3D) electromagnetic responses using the controlled source time domain electromagnetic method suffers from low accuracy of the early response calculation and difficulty in the convergence of the later response for large-scale models. To address these problems, we propose a method of decomposing the time domain electromagnetic response into a primary field and a secondary field. This approach can easily address the above issues. In this paper, we use a time domain finite difference method based on a non-uniform step size and staggered grid and use an iterative algorithm with a non-uniform step size to calculate the late time domain electromagnetic response under high power pulse source excitation. Several example simulations were compared with analytical and spectral Lanczos decomposition solutions and demonstrate the correctness of the 3D forward modeling method. The response of a 3D anomaly excited by an electric dipole source pulse current was analyzed. The calculated time domain response revealed that the field excited by the high power pulse source diffused in the earth over time and exhibited a secondary diffusion process of the anomalous field generated by the 3D anomaly. The numerical simulation results showed that the time domain electromagnetic responses excited by the pulse source were stable and effective. The amplitude of the anomalous response was much greater than that of the step source, the signal-to-noise ratio was greater, and the detectability was better. The method may be used in inversion of the time domain electromagnetic response if the calculation speed can be further improved.

Revisiting Exchange Rate Shocks on Macroeconomic Variables in China using Time-Varying VAR Model

In this study we analyze exchange rate shocks in China on its macroeconomic variables by apply TVP-VAR modeling approach. Three-dimensional impulse response functions reveal that GDP, CPI and interest rate are affected in the short run and long run. Our findings have important policy implications for the Chinese government conducting exchange rate policy.

Full wave simulation of arterial response under acoustic radiation force

With the ultimate goal of estimating arterial viscoelasticity using shear wave elastography, this paper presents a practical methodology to simulate the response of a human carotid artery under acoustic radiation force (ARF). The artery is idealized as a nearly incompressible viscoelastic hollow cylinder submerged in incompressible, inviscid fluid. For this idealization, we develop a multi-step methodology for efficient computation of three-dimensional response under complex ARF excitation, while capturing the fluid-structure interaction between the arterial wall and the surrounding fluid. The specific steps include (a) performing dimensional reduction through semi-analytical finite element formulation, (b) efficient finite element discretization using traditional and recent techniques. The computational efficiency is further enhanced by utilizing (c) modal superposition, followed by, where appropriate, (d) impulse response function. In addition to developing the methodology, convergence analysis is performed for a typical arterial geometry, leading to recommendations on various discretization parameters. At the end, the computational effort is shown to be several orders of magnitude less than the traditional, fully three-dimensional analysis using finite element methods, leading to a practical yet accurate simulation of arterial response under ARF excitations.

Enhancement of PVA packaging properties using calcined eggshell waste as filler and nanonutrient

With an understanding of the disadvantages of petroleum-based polymers and the need for biodegradable polymers and nanofillers to overcome the problems of natural polymers, we repurpose the waste materials as nanofiller for PVA polymer. Eggshell, an excess component in kitchen waste, can be calcined to calcium oxide that was used as a binder to enhance the PVA stability and physical and chemical properties. Application of calcium oxide was not only for strength improvements, but also to supply nutrients to the soil after degradation. The water-resistance property and degradation ability of films were studied completely by varying the PVA composition and CaO concentration. In addition to the degradation study, the influence of solubilised polymer solutions given to soil and their influence on plant growth were analysed. The impact of parameter variation (PVA, CaO, and glycerol) on the film properties like thickness (THI), water solubility (SOL), moisture content (MC), water absorption, water vapour transmission rate (WVTR), tensile strength (TS) and elongation (ELONG) was investigated using a three-level Box–Behnken response surface design, Pareto analysis of variance (ANOVA), and a second-order polynomial model. Three-dimensional response surface plots were generated to investigate the relationship between process variables and the responses.

Three-Dimensional Quantitative Tumor Response and Survival Analysis of Hepatocellular Carcinoma Patients Who Failed Initial Transarterial Chemoembolization: Repeat or Switch Treatment?

Simple SummaryTransarterial chemoembolization is the main therapy for patients with intermediate-stage hepatocellular carcinoma; it has demonstrated efficacy and survival benefits. However, treatment success cannot always be achieved after one treatment session. Using a quantitative 3D tumor-response assessment, we showed that a second transarterial chemoembolization in patients who initially do not respond to therapy results in both objective tumor response and survival benefits. Thus, at least two sessions should be performed before TACE is abandoned and alternative treatments are considered.Objectives: The purpose of this study was to assess treatment responses and evaluate survival outcomes between responders and non-responders after each transarterial chemoembolization (TACE) session using the 3D quantitative criteria of the European Association for the Study of the Liver (qEASL) in hepatocellular carcinoma (HCC) patients. Methods: A total of 94 consecutive patients who underwent MR imaging before and after TACE were retrospectively included. Volumetric tumor enhancement (qEASL) was expressed in cubic centimeters (cm3). The Kaplan–Meier method with the log-rank test was used to calculate the overall survival (OS) for the non-/responders. Results: In total, 28 (29.8%) patients showed a response after the first TACE. These responders demonstrated a clear trend toward longer OS compared with the non-responders (36.7 vs. 21.5 months, p = 0.071). Of the 43 initial non-responders who underwent a second TACE within 3 months and had complete follow-up imaging, 15/43 (34.9%) achieved a response, and their median OS was significantly longer than that of the 28 non-responders to the second TACE (47.8 vs. 13.6 months, p = 0.01). Furthermore, there was no significant difference in OS between the 28 patients who achieved a response after the first TACE and the 15 initial non-responders who achieved a response after the second TACE (36.7 vs. 47.8 months, p = 0.701). The difference in OS between the responders and non-responders after the third TACE was not significant (11.4 months vs. 13.5 months, p = 0.986). Conclusion: Our study quantitatively demonstrated that a second TACE can be beneficial in terms of tumor response and survival for HCC patients who do not initially respond to TACE.

Nonlinear vibratory energy exchanges in a meta-cell

Meta-materials are utilized for bringing passive attenuation solution especially in the acoustics and vibration domains. Generally speaking, they are composed of an array or a chain of meta-cells. Here the vibratory energy exchanges between particles of a nonlinear meta-cell are studied. The meta-cell is composed of an outer mass which houses an inner mass with a compound nonlinear restoring forcing term. It is globally non-smooth, containing pure cubic and piece-wise linear terms, which constitutes a new type of nonlinearity for such mass-in-mass cells. The complexified form of system equations is treated by the multiple time scale method to find out its fast and slow dynamics, leading to determination of the slow invariant manifold as well as the singular and equilibrium points of the system. The compound nonlinear restoring forcing function of the inner mass makes the global geometry of the slow invariant manifold to be different from those of systems with pure cubic nonlinearities, for example, including four singular lines and two distinct unstable zones. Amplitude dependency of the frequency of such a nonlinear system in the conservative form is represented by the backbone curves. Furthermore, detected equilibrium points for different external forcing amplitudes are represented by three-dimensional frequency response curves. Finally, analytical predictions are confronted with numerical results obtained by direct time integration of the system equations. An application of such system can be the passive control of main systems via embedding another nonlinear oscillator inside it. Moreover, such system can also be extended in the form of an array to create meta-materials.

Seismic overturning fragility analysis for freestanding building contents subjected to horizontal bidirectional floor motions

The rocking response of freestanding building contents simplified as rigid bodies was usually investigated in two dimensions with ground motions as the input, while their three-dimensional (3-D) rocking response subjected to horizontal bidirectional floor motions needs further investigation in both deterministic and probabilistic views. In this paper, the rocking response of freestanding 3-D rectangular blocks subjected to seismic excitations with two horizontal components are first investigated by shake table tests and finite element (FE) numerical simulation. An incremental dynamic analysis-based overturning fragility assessment method for the blocks within a building subjected to bidirectional ground motions is then proposed, using uncoupled nonlinear FE models of the block-building systems. The overturning fragility of six blocks within a four-story reinforced concrete frame structure is assessed. The influence of excitation directions, floor levels, block slenderness ratios (2.5, 3, 3.5 and 4), block sizes (size parameters of 91 mm, 182 mm and 364 mm) and intensity measurements (IMs) on the overturning fragility of the block is characterized. The experimental overturning fragility curves of three blocks in real conditions under bidirectional seismic excitations are finally obtained from the shake table tests. Rocking-torsional rotations are observed for the block with sliding not allowed. The block rocks around a side or a vertex while overturns around a side. Except the largest block, the block under bidirectional excitations is usually more and sometimes equally vulnerable to overturn in comparison to that under unidirectional excitations. The block on a higher floor is found to be more vulnerable to overturn than that on a lower floor considering the peak ground acceleration-based IM. These observations highlight on the significance of 3-D analysis for the rocking blocks considering floor acceleration amplification. This paper also enlarges the experimental database of seismic rocking response of rectangular blocks under bidirectional horizontal motions.

Response assessment methods for patients with hepatic metastasis from rare tumor primaries undergoing transarterial chemoembolization

PurposeThis study assessed the response to conventional transarterial chemoembolization (cTACE) in patients with liver metastases from rare tumor primaries using one-dimensional (1D) and three-dimensional (3D) quantitative response assessment methods, and investigate the relationship of lipiodol deposition in predicting response. Materials and methodsThis retrospective bicentric study included 16 patients with hepatic metastases from rare tumors treated with cTACE between 2002 and 2017. Multi-phasic MR imaging obtained before and after cTACE was used for assessment of response. Response evaluation criteria in solid tumors (RECIST) and modified-RECIST (mRECIST) were utilized for 1D response assessment, and volumetric RECIST (vRECIST) and enhancement-based quantitative European Association for Study of the Liver EASL (qEASL) were used for 3D response assessment. The same day post-cTACE CT scan was analyzed to quantify intratumoral lipiodol deposition (%). ResultsThe mean and standard deviation (SD) of diameter of treated lesions per targeted area was 7.5 ± 5.4 cm, and the mean and SD of number of metastases in each targeted area was 4.2 ± 4.6. cTACE was technically successful in all patients, without major complications. While RECIST and vRECIST methods did not allocate patients with partial response, mRECIST and qEASL identified patients with partial response. Intratumoral lipiodol deposition significantly predicted treatment response according qEASL (R2 = 0.470, p < 0.01), while no association was shown between lipiodol deposition within treated tumor area and RECIST or mRECIST (p > 0.212). Conclusion3D quantitative volumetric response analysis can be used for stratification of response to cTACE in patients with hepatic metastases originating from rare primary tumors. Lipiodol deposition could potentially be used as an early surrogate to predict response to cTACE.

Three-dimensional thermoelectroelastic analysis of structures with distributed piezoelectric sensors and actuators with temperature-dependent material properties

In this paper, a geometrically exact hybrid-mixed four-node laminated solid-shell element with piezoelectric patches with temperature-dependent material properties through the sampling surfaces (SaS) formulation is developed. The SaS formulation is based on the choice of SaS, parallel to the middle surface and located at Chebyshev polynomial nodes within the layers, to introduce the temperatures, displacements and electric potentials of these surfaces as basic shell unknowns. The outer surfaces and interfaces are also included into a set of SaS. Such a choice of unknowns with the use of Lagrange polynomials in the through-thickness approximations of temperatures, temperature gradient, displacements, strains, electric potential and electric field leads to a very compact higher-order thermopiezoelectric shell formulation. To implement efficient analytical integration throughout the solid-shell element, the extended assumed natural strain method is employed for all components of the temperature gradient, strain tensor and electric field vector. The developed hybrid-mixed four-node laminated solid-shell element with piezoelectric sensors and actuators is based on the extended Hu-Washizu variational principle and shows superior performance in the case of coarse meshes. This can be useful for the three-dimensional temperature-dependent response of laminated composite shells with piezoelectric patches, since the SaS formulation allows one to obtain the numerical solutions with a prescribed accuracy, which asymptotically approach the exact solutions of thermopiezoelectricity as a number of SaS tends to infinity.

Time History Method of Three-Dimensional Dynamic Stability Analysis for High Earth-Rockfill Dam and Its Application

Accurately grasping the stability characteristics of high earth-rockfill dam slopes is the key to the seismic safety evaluation of dams. In this research, the development and application of the common methods for slope stability analysis are reviewed firstly. Then, a three-dimensional dynamic time history stability analysis method is presented, and corresponding software is developed based on the sliding surface finite element stress method combined with the three-dimensional finite element dynamic response. This method makes the three-dimensional dynamic stability analysis efficient, and the effectiveness of this software is verified. Finally, the two-dimensional (2D) and three-dimensional (3D) dynamic stability analyses of a high concrete face dam are carried out, and the stability of the dam’s downstream slope under seismic load is studied. The results indicate that there are many differences between the results of the traditional 2D and 3D stability analyses. The time history of the safety factor, local safety behavior, overall shape and spatial position of the potential sliding body, and even the sliding process of failure can be captured with 3D stability analysis.

Response Surface Optimisation of Polydimethylsiloxane (PDMS) on Borosilicate Glass and Stainless Steel (SS316) to Increase Hydrophobicity.

Particle deposition on the surface of a drying chamber is the main drawback in the spray drying process, reducing product recovery and affecting the quality of the product. In view of this, the potential application of chemical surface modification to produce a hydrophobic surface that reduces the powder adhesion (biofouling) on the wall of the drying chamber is investigated in this study. A hydrophobic polydimethylsiloxane (PDMS) solution was used in the vertical dipping method at room temperature to determine the optimum coating parameters on borosilicate glass and stainless steel substrates, which were used to mimic the wall surface of the drying chamber, to achieve highly hydrophobic surfaces. A single-factor experiment was used to define the range of the PDMS concentration and treatment duration using the Response Surface Methodology (RSM). The Central Composite Rotatable Design (CCRD) was used to study the effects of the concentration of the PDMS solution (X1, %) and the treatment duration (X2, h) on the contact angle of the substrates (°), which reflected the hydrophobicity of the surface. A three-dimensional response surface was constructed to examine the influence of the PDMS concentration and treatment duration on contact angle readings, which serve as an indicator of the surface’s hydrophobic characteristics. Based on the optimisation study, the PDMS coating for the borosilicate glass achieved an optimum contact angle of 99.33° through the combination of a PDMS concentration of X1 = 1% (w/v) and treatment time of X2 = 4.94 h, while the PDMS coating for the stainless steel substrate achieved an optimum contact angle of 98.31° with a PDMS concentration of X1 = 1% (w/v) and treatment time of X2 = 1 h. Additionally, the infrared spectra identified several new peaks that appeared on the PDMS-treated surfaces, which represented the presence of Si-O-Si, Si-CH3, CH2, and CH3 functional groups for the substrates coated with PDMS. Furthermore, the surface morphology analysis using the Field Emission Scanning Electron Microscopy (FESEM) showed the presence of significant roughness and a uniform nanostructure on the surface of the PDMS-treated substrates, which indicates the reduction in wettability and the potential effect of unwanted biofouling on the spray drying chamber. The application of PDMS and PTFE on the optimally coated substrates successfully reduced the amount of full cream milk particles that adhered to the surface. The low surface energy of the treated surface (19–27 mJ/m2) and the slightly higher surface tension of the full cream milk (54–59 mJ/m2) resulted in a high contact angle (102–103°) and reduced the adhesion work on the treated substrates (41–46 mJ/m2) as compared to the native substrates.

Research on enhancement of heat transfer by vortex-induced vibration of heat exchange tube bundles with elastic joints

In the field of fluid-induced vibration enhanced heat transfer in heat exchangers, the elastic tube bundle structure currently cannot reach the ideal state of fluid-induced vibration enhanced heat transfer and is prone to fatigue failure. In response to this problem, this article proposes to make full use of the shell-side fluid vortex-induced elastic tube bundle vibration to achieve the purpose of enhancing heat transfer, and innovatively design heat transfer tube bundles with elastic joins that can adapt to large-amplitude vibration and be not damaged by structural fatigue. Here, the dynamic modal characteristics and the fluid–solid coupling vibration heat transfer characteristics of the single heat transfer tube bundle with elastic joints are studied by numerical calculation. The results show that the low-order modes of this tube bundle include one-dimensional mode, two-dimensional mode, and three-dimensional mode. When the flow velocity is 0.1 m/s≤ u≤ 0.2 m/s, the fluid vortex-induced tube bundle produces a two-dimensional vibration response with a maximum amplitude of 9.2 mm. At the same time, the tube bundle vibration enhances heat transfer significantly. When the flow velocity u= 0.12 m/s, compared with the static circle tube under the same working condition, the heat transfer coefficient is increased by 11.8%. When the flow velocity u > 0.2 m/s, the fluid can stimulate the three-dimensional vibration response of the tube bundle, but the circular tube vibration no longer has the function of enhancing heat transfer. The research in this article will enrich the development of fluid-induced vibration enhanced heat transfer theory and promote its engineering application.

3D response surface modeling based in-situ assessment of physico-mechanical characteristics of alluvial soils using dynamic cone penetrometer

Dynamic cone penetrometer (DCP) is the quickest and cheapest in-situ probing apparatus to estimate the soil stiffness; however, insufficient correlations are available to directly assess various physico-mechanical characteristics of natural alluvial soils using DCP. The key purpose of this study is to statistically equate the in-situ DCP test outcomes to different physico-mechanical characteristics of alluvial soils. For this purpose, in-situ DCP tests were performed at 26 different locations in the Indus plane, and corresponding undisturbed specimens were collected for laboratory testing. Various physico-mechanical characteristics of soil i.e., natural water content (wn), natural dry unit weight (γd), unconfined compressive strength (qu), deformation modulus (E50), strain at failure (εf), natural void ratio (en) and California bearing ratio (CBR) were determined in the laboratory. Initially, the regression-based models were established for γd, qu, E50, εf, en, and CBR using dynamic cone penetrometer index (DCPI) as a solitary predictor. Afterward, predictive models of the aforementioned parameters were developed based on wn integrated DCPI by quantifying the best-fit trend line and three-dimensional (3D) response surface among pertinent dependent and independent variables. In addition, it is found that the models developed using 3D response surface modeling hold 8.2–42.4% lesser error than the regression-based models developed in the current study. Moreover, results show that the DCP based assessment of soil is influenced by wn and independent of consistency limits and soil type of the alluvial soils.

Machine learning for board-level drop response of BGA packaging structure

Board-level drop responses are critical to evaluate the mechanical reliability of solder joints to serve as electrical and mechanical connections in electronic devices to resist failure due to drop impact. A machine learning (ML) model based on the back propagation (BP) method is proposed for predicting three-dimensional board-level drop responses of the ball grid array (BGA) packaging structures. Compared with conventional finite element (FE) simulations with solid elements, the proposed approach with a deep neural network is more than three orders of magnitude faster in terms of computational efficiency. More importantly, detailed stress and strain of all solder joints and also the warpage of the printed circuit board (PCB) can be accurately predicted throughout the drop process. According to the contact type between BGA packaging structure and rigid ground, the drop conditions are divided into three types: surface contact, line contact and point contact. After training the ML model, the obtained nonlinear mapping relation can well predict the mechanical response of solder joints in BGA packaging structures. To significantly extend the application scope, the trained ML model could reasonably predict the dynamic responses of BGA structures with the drop angles which are beyond the training samples. Compared with FE results, the prediction accuracy of the proposed ML model is objectively measured by the Pearson correlation coefficient which is found to be above 0.95 after estimating the stress, strain and energy density of solder joints and PCB warpage. Except for those stress, train and energy density values close to 0, the prediction errors are mostly less than 10% compared with the finite element simulation values. Therefore, it is affirmed that the computational efficiency and accuracy of the proposed ML method are satisfactory to replace the traditional time-consuming FE modeling for predicting the dynamic responses of board-level BGA packaging structures even under more extreme and complicated loading conditions.