Changes In Material Properties Research Articles

Magnetic and structural properties of multiple recycled and sustainable sintered Nd-Fe-B magnets

Scrap magnets from magnetic resonance tomography (MRT) devices with nominal composition of Nd28.04Dy0.80Tb0.44FebalB1.06Co1.65Al0.34Ga0.22Cu0.18 (wt. %) were recycled multiple times with the so-called magnet-to-magnet or functional recycling approach employing hydrogen decrepitation. Changes in different material properties like chemical composition, impurity content, particle size, magnetic properties, microstructure and degree of alignment were investigated in detail. The multiple processing and recycling of the material leads to a decrease in texture, orientation and the resulting magnetic properties of the recycled magnets, respectively. Meanwhile impurities and particle size of the material increase through several milling and sintering processes. Different amounts of Nd hydride were mixed with the recyclate to improve the properties. With 4 wt. % Nd hydride the density of the recycled magnets can be fully restored. It was shown that magnetic properties of the recycled magnets meet the specification of primary magnets even after several cycles. However, they outperform magnets produced from primary materials in terms of sustainability with lower ecological and social footprints. Furthermore, they can lower the production cost of products using permanent magnets by reducing the energy consumption and raw material costs.

Numerical study on the performance of adsorption refrigeration system with finned bed structure paired with MOF-water as working fluid

A single-bed finned tube adsorption refrigeration system model was established to compare the adsorption characteristics of three metal organic framework materials, MIL-101(Cr), MIL-101(Cr)/CaCl2-10%, MIL-101(Cr)/ CaCl2-20%. The change of material properties under different thickness/length/number of fins was characterized, and the most suitable adsorption bed structure for different materials was obtained. The results show that the number of fins has little effect on the COP and specific cooling power of the material in the system. Choosing thinner fins can improve the COP of the system. With the increase of fin height, the COP showed a trend of increasing first and then decreasing. The three materials, MIL-101(Cr), MIL-101(Cr)/CaCl2-10%, MIL-101(Cr)/CaCl2-20%, obtained the highest COP when the fin heights were 50 mm, 60 mm, and 70 mm, respectively. The maximum specific cooling power was obtained when the fin heights were 20 mm, 60 mm, and 70 mm, which were 21.7 W/kg, 90.1 W/kg, and 174.5 W/kg, respectively. The height of the fin has a great influence on the performance of the system. When designing the adsorption bed, the appropriate fin height should be selected for the specific adsorbent.

Impact of acetic acid exposure on metal contact degradation of different crystalline silicon solar cell technologies

Degradation due to acetic acid in photovoltaic (PV) modules has been a commonly observed phenomenon for both damp-heat exposure and outdoor operations. Acetic acid is a degradation byproduct of ethylene-vinyl acetate (EVA), a common module encapsulant. To address this issue, robust metallization pastes and cell technologies are being developed. However, it is important to assess how these technologies perform in an acetic acid environment and withstand degradation before they are implemented in the solar market. In this work, we investigate the impact of acetic acid exposure on four different cell groups: monofacial passivated emitter and rear contact (PERC) cells with advanced telluride-based front contact pastes, bifacial PERC cells with novel aluminum rear contact pastes, bifacial tunnel oxide passivated contacts (TOPCon) cells, and silicon heterojunction (SHJ) cells. These cells were exposed to acetic acid for different time increments. The recombination losses were characterized by Suns- V OC , and multi-variate regression analysis of intensity-dependent photoluminescence (PL) images with Griddler AI. Resistive losses were tracked with the transmission line method (TLM). Samples showing severe performance degradation were selected for further materials characterization to understand the root cause. Top-down and cross-sectional scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were performed to investigate the change in materials properties. Our study shows that the front contacts of the bifacial TOPCon cells and monofacial PERC cells were significantly affected by acetic acid exposure. The SHJ cells were found to be the most stable. • Effect of acetic acid on metallization pastes and cell technologies was investigated. • Front Ag-Al contacts for Bifacial TOPCon cells degrade the most due to acid exposure. • Monofacial PERC cells with Pb-free Te-O paste is the second group that is affected. • Bifacial PERC cells were stable with Al back contacts showing no signs degradation. • SHJ cells were the most stable group in this experiment.

Effect of non-enzymatic glycation on collagen nanoscale mechanisms in diabetic and age-related bone fragility.

Age and diabetes have long been known to induce an oxidative reaction between glucose and collagen, leading to the accumulation of advanced glycation end-products (AGEs) cross-links in collagenous tissues. More recently, AGEs content has been related to loss of bone quality, independent of bone mass, and increased fracture risk with aging and diabetes. Loss of bone quality is mostly attributed to changes in material properties, structural organization, or cellular remodeling. Though all these factors play a role in bone fragility disease, some common recurring patterns can be found between diabetic and age-related bone fragility. The main pattern we will discuss in this viewpoint is the increase of fibrillar collagen stiffness and loss of collagen-induced plasticity with AGE accumulation. This study focused on recent related experimental studies and discusses the correlation between fluorescent AGEs content at the molecular and fibrillar scales, collagen deformation mechanisms at the nanoscale, and resistance to bone fracture at the macroscale.

Design and validation of a suction device to reduce cross-contamination in multi-material laser-based powder bed fusion

Powder suction modules for additive manufacturing systems in the field of multi-material laser powder bed fusion (PBF-LB/M) have a critical influence on the quality of the manufactured components. In particular, metal powder cross-contamination originating from insufficient removal of foreign particles during multi-material processing can lead to undesired changes in material properties. In this paper, a suction device was simulated, designed, and validated to reduce cross-contamination. Requirements and necessary characteristic values of the multi-material PBF-LB/M system, the powder suction module, and the materials used were determined. Furthermore, an iterative simulative method and procedure for the design of suction devices was applied. For this purpose, a flattened bell-shaped geometry with flow-optimized fins was presented. This design led to both a high flow velocity and a homogenous velocity distribution at the nozzle inlet for full-surface multi-material PBF-LB/M suction modules. The developed method was validated by applying it to the material combination of tool steel 1.2709 and copper alloy CW106C. The aim was to reduce the cross-contamination generated during the in-process on an SLM 280HL multi-material PBF-LB/M system. Multi-material samples were built using the original nozzle design as well as the newly developed improved powder suction module and investigated in terms of resulting cross-contamination using energy-dispersive X-ray spectroscopy. The improved suction module had a significantly higher flow velocity and a more homogenous velocity distribution at the nozzle inlet compared to the original suction module. Cross-contamination of the manufactured multi-material samples was reduced by up to 93 % due to the improved suction model.

Electromagnetic-Thermal Modeling of Nonlinear Magnetic Materials

A nonlinear electromagnetic (EM)-thermal coupled solver is developed for modeling ferromagnetic materials widely used in electric motors. To accurately predict machine performance, the time-domain finite element method is employed to solve this multiphysics problem. By adopting the nonlinear B-H models to account for hysteresis effects, magnetic core losses are computed as the major sources of power dissipation for magnetic materials. The resulting temperature change is then obtained and its effect on the magnetic properties is subsequently evaluated. Due to different time scales of EM field variations and heat transfer processes, different time step sizes are adopted to enhance the simulation speed. During thermal time marching, the EM solver is invoked adaptively based on material property changes, and EM losses are calculated and updated through extrapolation, resulting in an efficient EM-thermal coupling scheme. Numerical examples are presented to validate the accuracy and capabilities of the proposed EM-thermal co-simulation framework.

Self-Adaptive Overtemperature Protection Materials for Safety-Centric Domestic Induction Heating Applications

Security aspects in the household sphere have become a major concern in modern societies. In particular, regardless of the technology used, users increasingly appreciate a protection system to prevent material damage in the case of human errors or distractions during the cooking process. This paper presents a sensorless method for detecting and limiting overtemperature, unique to induction cooktops, based on their specific features, such as automatic pot detection and load power factor estimation. The protection system exploits the change in the load material properties at certain temperatures, the effect of which may be enhanced by arranging a multilayer structure comprising a low Curie temperature alloy and an aluminum layer. The proposed multilayer load exhibits two differentiated states: a normal state, where the cookware is efficiently heated, and a protection state, above the safety temperature, where the power factor abruptly decreases, limiting the overheating and making the state easily detectable by the cooktop. This method of overtemperature self-protection uses the electronics of conventional induction cooktops; therefore, no other sensors or systems are required, reducing its complexity and costs. Simulation and experimental results are provided for several cookware designs, thereby proving the feasibility of this proposal.

MODELLING AND ANALYSIS OF INITIAL STRESS STATE IN A THIN-WALL CYLINDER WITH VARIABLE CHARACTERISTICS

A linearized model of prestressed elastic body vibrations is described in terms of the nonsymmetric Piola stress tensor, and a weak statement of the original problem is given. With the help of the Lagrange variational principle, we construct a statement of the problem of steady axisymmetric oscillations of a thin-walled (shell-like) cylinder with variable material properties in the presence of an inhomogeneous prestress field. The motion equations, essential and natural boundary conditions are formulated. Integral characteristics are introduced that average the change in prestresses and material properties over the shell thickness. On the basis of the model presented, the problem on steady-state vibrations of a functionally graded prestressed cylindrical shell is numerically investigated via the shooting method; the influence of the laws of change in material modules and prestress components on dynamic characteristics (e.g., amplitude-frequency characteristics, natural vibration frequencies) is analyzed, a comparative analysis of the solutions is carried out depending on the thin-walled parameter. For the considered cylindrical shell with axial inhomogeneity, based on the acoustic sounding data, we study the inverse problem of restoring two laws of prestress inhomogeneity characterizing the nonuniform initial stress-strain state of tension or inflation. As additional information, we consider the measurement data of the displacement components on the cylinder's surface, given in a set of points at a certain frequency of steady-state oscillations; in such a case, the material characteristics are considered to be known and may depend on the axial coordinate, which makes it possible to set an arbitrary functional gradient along the axis of the cylinder. The mode of probing loading is determined by specifying the traction type and oscillation frequency. Explicit formulas for the desired laws of prestress inhomogeneity are obtained, and computational experiments are carried out to restore them. A high accuracy of reconstruction is revealed far from the ends of the cylinder when probing at a frequency in the vicinity of the first resonance.

Preliminary results on a near-real-time rock slope damage monitoring system based on relative velocity changes following the September 5, 2022 MS 6.8 Luding, China earthquake

Relative seismic velocity change (dv/v) is important for monitoring changes in subsurface material properties and evaluating earthquake-induced rock slope damage in a geological disaster-prone region. In this paper, we present a rapid damage assessment on three slow-moving rock slopes by measuring dv/v decrease caused by the 2022 ​MS 6.8 Luding earthquake in Southwest China. By applying the stretching method to the cross-correlated seismic wavefields between sensors installed on each slope, we obtain earthquake-induced dv/v decreases of ∼2.1%, ∼0.5%, and ∼0.2% on three slopes at distances ranging from ∼86 to ∼370 ​km to the epicenter, respectively. Moreover, based on seismic data recorded by 16 sensors deployed on the rock slope at a distance of ∼370 ​km away from the epicenter, a localized dv/v decease region was observed at the crest of the slope by calculating the spatial dv/v images before and after the earthquake. We also derive an empirical in situ stress sensitivity of −7.29✕10−8/Pa by relating the dv/v change to the measured peak dynamic stresses. Our results indicate that a rapid dv/v assessment not only can help facilitate on-site emergency response to earthquake-induced secondary geological disasters but also can provide a better understanding of the subsurface geological risks under diverse seismic loadings.

Material Changes in Electrocatalysis: An In Situ/Operando Focus on the Dynamics of Cobalt‐Based Oxygen Reduction and Evolution Catalysts

AbstractThe shift towards cheaper, non‐platinum group metal electrocatalyst materials for clean energy technologies is coupled with challenges in maintaining long‐term performance. For practical purposes, electrocatalytic stability typically focuses on catalyst electrochemical performance over time. However, a deeper understanding of catalyst material property changes during operation is needed to enable material‐specific design strategies for long‐term stabilization. In the last several decades, improvements in material characterization techniques have made it possible to probe the composition, structure, and degradation products of catalysts in situ/operando. Herein we review the current understanding of in situ/operando material stability of Co‐based electrocatalysts for the oxygen evolution (OER) and reduction reactions (ORR) in acidic and alkaline environments. We focus on in situ/operando materials characterization of three categories of Co‐based OER/ORR catalysts: oxides and (oxy)hydroxides, mixed‐metal catalysts, and non‐oxide materials. This review aims to compile and compare the results from multiple studies and techniques to provide insight into the role that the starting material, pH, and applied potential have on the active surface and stability of Co‐based materials. We conclude by highlighting directions that have been underexplored with opportunities for continued research including improving in situ/operando characterization, methods to probe long‐term material changes, and the development of operando studies on full‐scale devices. Using Co‐based materials as a case study, this review shows the vital role that in situ/operando characterization must play in the future of improving electrocatalyst stability.

Effects of Field Aging on Material Properties and Rutting Performance of Asphalt Pavement

This study evaluates field asphalt aging based on material property changes in pavement with time, and investigates if such changes could have an impact on field rutting performance. Four projects from three different climate zones were monitored as part of the NCHRP 9-49A project at two stages: during pavement construction and two to three years after opening it to traffic. Construction information were collected, and field cores were drilled at both stages to evaluate the material properties of recovered asphalt binder and asphalt mixture. Field rut depth was also measured. In addition, pavement structure, climate and base/subgrade modulus information were also obtained. Results indicate that the asphalt mixture stiffening is caused in major part by asphalt aging. However, the effect of asphalt aging on pavement mixture property may not follow a proportional liner trend. The parameters that are most sensitive to field ageing are MSCR R3.2 and dynamic modulus. It is also found that the variables which showed a good ranking trend with the field rut depth are climate condition (relative humidity, high temperature hour, solar radiation), material properties (Hamburg rut depth, rutting resistance index, high temperature performance grade, MSCR, and dynamic modulus, base and subgrade moduli), as well as air voids.

Effects of Side-Chain Length and Functionality on Polar Poly(dioxythiophene)s for Saline-Based Organic Electrochemical Transistors.

Understanding the impact of side chains on the aqueous redox properties of conjugated polymers is crucial to unlocking their potential in bioelectrochemical devices, such as organic electrochemical transistors (OECTs). Here, we report a series of polar propylenedioxythiophene-based copolymers functionalized with glyme side chains of varying lengths as well as an analogue with short hydroxyl side chains. We show that long polar side chains are not required for achieving high volumetric capacitance (C*), as short hydroxy substituents can afford facile doping and high C* in saline-based electrolytes. Furthermore, we demonstrate that varying the length of the polar glyme chains leads to subtle changes in material properties. Increasing the length of glyme side chain is generally associated with an enhancement in OECT performance, doping kinetics, and stability, with the polymer bearing the longest side chains exhibiting the highest performance ([μC*]OECT = 200 ± 8 F cm-1 V-1 s-1). The origin of this performance enhancement is investigated in different device configurations using in situ techniques (e.g., time-resolved spectroelectrochemistry and chronoamperometry). These studies suggest that the performance improvement is not due to significant changes in C* but rather due to variations in the inferred mobility. Through a thorough comparison of two different architectures, we demonstrate that device geometry can obfuscate the benchmarking of OECT active channel materials, likely due to contact resistance effects. By complementing all electrochemical and spectroscopic experiments with in situ measurements performed within a planar OECT device configuration, this work seeks to unambiguously assign material design principles to fine-tune the properties of poly(dioxythiophene)s relevant for application in OECTs.

Stability analysis of an old earth Samarkand Dam in Kazakhstan under rapid drawdown conditions

Despite being potential historical sites, old embankment dams are subjected to many stability challenges due to many factors, including a lack of sufficient stability assessment tools by the time the dam was built and changes in embankment material properties induced by natural and human activities. Therefore, with the current advancement in technology is of great importance to investigate the state of old embankment dams under different potential loading conditions. The stability challenges become of more significant concern when the embankment is subjected to a rapid drawdown loading scenario. In this study, the Samarkand dam located in Karaganda province in Kazakhstan which was put into operation in 1941 is investigated in terms of seepage and slope stability with the help of numerical modelling. Both steady and transient (rapid drawdown) flow conditions are taken into consideration. e finite element method-based modelling is achieved using SEEP/W and SLOPE/W of the GeoStudio software. From the analysis results, it was observed that the old dam can be subjected to a potential failure under rapid drawdown conditions as the minimum factor of safety values were decreasing with the increase in the drawdown rates. For instance, the minimum factor of safety from the instantaneous drawdown rate was equivalent to 32.85% less than the factor of safety retrieved from the long-term steady-state conditions. Also, from Analysis of Variance (ANOVA), a p-value of 9.97× 10-29 was obtained after subjecting the factor of safety values from instantaneous, 5 days, 10 days, and 1 m per day drawdown rates to ANOVA, indicating that the factor of safety differences among the analyzed drawdown rates were statistically significant.

An experimental investigation on the effectiveness of damping changes for damage detection in a Fibre Reinforced Plastic Plate

Fibre reinforced plastics (FRP) are extensively used because of their high specific strength and stiffness. However, throughout their service life, such materials are susceptible to damages, which when accumulated may result in catastrophic failure. Studies on effects of stiffness loss due to damage has been exercised by quite a large number of researchers but very less investigators have involved the variations in dissipative behaviour in combination with such stiffness loss. However, damage in these structures not only causes local reduction of stiffness but is also observed with increased dissipation behaviour. One of the most convenient ways to carry out health monitoring exercise to detect damages is to conduct systematic vibration testing. The present study investigates the likely changes in natural frequencies and mode shapes of a rectangular FRP composite plate along with damping factors due to the induced damage. The FRP plate considered has been modal tested and dynamic responses i.e., natural frequencies, mode shapes and modal damping factors are derived through curve-fitting technique from the frequency response function measurements. In this study, changes in dynamic responses due to a locally induced damage in the FRP plate is studied. For this, in order to maximize the effects of local reduction in the stiffness on the modal parameters, a partial-cut is provided in a localised region of the plate in the first damage case. In the second damage scenario, the partially-cut area has been filled with epoxy resin matrix to create a region with localised change in material properties and with limited stiffness loss. Damping changes has been observed to be significant and more sensitive than variations in natural frequencies and mode shapes. The study suggests that damping parameters along with stiffness changes together can be put into practice to develop an effective vibration-based health monitoring scheme

Bending Analysis of Orthotropic Plate using 5th Order Shear Deformation Theory

A composite material is a combination of different material which can be assembled to provide required engineering properties like bending, buckling, stiffness etc. It can give better properties than those of individual components. A lamina is the building block of modern composite laminated structures. A lamina is also known as a ply, or a layer. A laminate has several layers of lamina, or laminae. Since the early years of engineering, various types of laminated composite materials have been used in various engineering fields, such as in aerospace, military and automotive industries that are subjected to high temperatures. Thermal stress caused due to change in temperature, increase in temperature causes the changes in material properties of a plate which in turn complicates the analysis and design and may affect the structure also. Therefore, the analysis of thermal stress in design of structure is very important. A critical review of available literature for the prediction of the behaviour of laminated composites under thermal conditions is carried out and summarized. This work attempts to review the studies carried out from 2000 on laminated composite plates by representing classification based on Classical laminate plate concept, First order shear deformation theory, Higher order shear deformation theory, Layerwise theory and Thermal stress on laminated plates.

Review on laminated composite plates

A composite material is a combination of different material which can be assembled to provide required engineering properties like bending, buckling, stiffness etc. It can give better properties than those of individual components. A lamina is the building block of modern composite laminated structures. A lamina is also known as a ply, or a layer. A laminate has several layers of lamina, or laminae. Since the early years of engineering, various types of laminated composite materials have been used in various engineering fields, such as in aerospace, military and automotive industries that are subjected to high temperatures. Thermal stress caused due to change in temperature, increase in temperature causes the changes in material properties of a plate which in turn complicates the analysis and design and may affect the structure also. Therefore, the analysis of thermal stress in design of structure is very important. A critical review of available literature for the prediction of the behaviour of laminated composites under thermal conditions is carried out and summarized. This work attempts to review the studies carried out from 2000 on laminated composite plates by representing classification based on Classical laminate plate concept, First order shear deformation theory, Higher order shear deformation theory, Layerwise theory and Thermal stress on laminated plates.

Damage Detection of FRP Composite Plates from Dynamical Responses using Finite Element Model Updating: Equivalent Material Properties as Parameters

Fibre reinforced plastic (FRP) composite structures are extensively used in weight sensitive applications, such as in aircrafts, ships, etc. Such structures are susceptible to damages during their usual operation or during extreme loading from environment. Due to the anisotropic nature of FRP composite plates, damage detection is difficult for such layered materials particularly when the damage site is inaccessible. The localised loss of stiffness resulting from damage is reflected into the global dynamic responses of such structures. Finite element model updating is a convenient inverse approach in which these changes in stiffness due to damages are estimated from measured dynamical responses using optimization. The equivalent stiffness changes can be expressed in terms of either geometric or material property or both. In most of the cases, changes in geometric parameters physically represent the actual damage scenario with larger sensitivity. On the other hand, material property changes in the damaged area are a very convenient parameter to deal with. In the present work, updating parameters in the finite element model updating procedure are chosen in terms of material property. Detection of local stiffness changes from experimentally measured natural frequencies, mode shapes and/or frequency response functions are investigated. Experimental modal testing is performed on a rectangular FRP composite plate both in its undamaged and damaged state. Baseline finite element model of the composite plate is correlated with experimental model, followed by a sensitivity based finite element model updating algorithm. The results show the rapid convergence and accurate determination of local stiffness change in terms of elastic material parameters alone in all three orthogonal directions. This indicates that material properties like the in-plane Young’s moduli and in-plane Shear modulus within the localised region of damage, can well be used as convenient means for detecting equivalent stiffness loss in damaged structures.

Effect of electrosurgical energy on suture material. An experimental study

BACKGROUND: The instructions for use of the suture material or coagulation tool do not describe the changes that may occur when they interact. A review of the literature found a small number of publications on changes in the physical properties of the suture material when exposed to chemical and mechanical factors. However, this is not enough to predict the effects of energy on the suture material and, as a result, on wound healing or the quality of the postoperative scar.
 AIM: To determine and measure the effect of the energy used for coagulation on the strength of the suture material.
 MATERIALS AND METHODS: In the experimental research, data on changes in the strength of 20 different filaments after exposure to the energy used for coagulation were analyzed in comparison with control samples.
 RESULTS: Research resulted in obtaining both expected or predicted indicators of changes in the strength of threads, and vice versa, absolutely unexpected results, which only confirms the significance of the research. Most of the filaments have lost their original strength after exposure to energy. However, some threads have become, on the contrary, stronger, despite the apparent destructive effect.
 CONCLUSIONS: The coagulation energy used in the ligature field changes the physical properties of the filaments. Therefore, in some cases it is worth abandoning the use of a certain type of energy and using another well-known method of hemostasis.

Spatial and Temporal Mapping of Articular Cartilage Poro-Viscoelastic Material Properties Using Indentation.

Biphasic poro-viscoelastic constitutive material model (BPVE) captures both the fluid flow dependent and independent behavior of cartilage under stress relaxation type indentation. A finite element model based on BPVE formulation was developed to explore the sensitivity of the model to Young's modulus, Poisson's ratio, permeability, and viscoelastic constitutive parameters expressed in terms of Prony series coefficients. Then we fit the numerical model to experimental force versus time curves from stress relaxation indents on bovine tibial plateaus to extract the material properties. Measurements were made over the period of two days to capture the material property changes that resulted from trypsin-induced degradation. We measured spatial and temporal changes in mechanical properties in the cartilage. The areas of degradation were characterized by an increase in both permeability and summation of Prony series shear relaxation amplitude constants. These findings suggest that cartilage degradation reduces the intrinsic viscoelastic properties of the solid phase of the tissue in addition to impairing its capacity to offer frictional drag to the interstitial fluid flow (permeability). The changes in material properties are measurable well before structural degradation occurs.

Theory for a non-invasive diagnostic biomarker for craniospinal diseases

Monitoring intracranial pressure (ICP) and craniospinal compliance (CC) is frequently required in the treatment of patients suffering from craniospinal diseases. However, current approaches are invasive and cannot provide continuous monitoring of CC. Dynamic exchange of blood and cerebrospinal fluid (CSF) between cranial and spinal compartments due to cardiac action transiently modulates the geometry and dielectric properties of the brain. The resulting impedance changes can be measured and might be usable as a non-invasive CC surrogate. A numerically robust and computationally efficient approach based on the reciprocity theorem was developed to compute dynamic impedance changes resulting from small geometry and material property changes. The approach was successfully verified against semi-analytical benchmarks, before being combined with experimental brain pulsation data to study the information content of the impedance variation. The results indicate that the measurable signal is dominated by the pulsatile displacement of the cortical brain surface, with minor contributions from the ventricular surfaces and from changes in brain perfusion. Different electrode setups result in complementary information. The information content from the investigated three electrode pairs was employed to successfully infer subject-specific brain pulsation and motion features. This suggests that non-invasive CC surrogates based on impedance monitoring could be established.