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Thermal aging and ultraviolet (UV) irradiation are used as methods to prepare samples of kraft paper spanning its full lifecycle within a high-voltage transformer, from new to end of life. The mechanical break strain is correlated with the degree of polymerization (DP), representing a progressive deterioration of mechanical properties during aging. Subsequent exposure to oil flow mimicking both normal plant operation and reclamation activities shows that aged paper exposed to high rates of flow experiences noticeable surface roughening. Despite this, no measurable erosion occurs even after long-term temperature/flow cycling in used mineral oil containing a notable particulate content. This indicates that kraft paper is unlikely to be eroded by normal reclamation activities, even in a severely aged asset. This confirms the validity of using this approach to extend plant life. [ABSTRACT FROM AUTHOR]

Paper-type gas diffusion layer (GDL) plays the role of structural support, mass transport, electron and heat transfer in the fuel cell. The deformation and fracture behavior of paper-type GDL directly determines its physical characteristics. In this paper, we obtained the distribution function of fiber length among intersections using statistical analysis. Based on the bending theory and fracture analysis, the deformation model and the maximum allowable pressure criterion of paper-type GDL are established. The deformation modulus is related to the modulus and the initial volume fraction of carbon fiber, with an ideal value of 1.4 MPa. The tensile fracture is the main form of fiber fracture. The maximum allowable pressure is related to the expected fracture probability, the strength and the initial volume fraction of carbon fiber. The residual strain increases and the deformation modulus decreases with load range, which means that the strength of the paper-type GDL is weakened when residual strain occurs. [Display omitted] • The fiber length between intersections obeys exponential distribution function. • The compression deformation model of paper-type GDL is established. • The maximum allowable pressure criterion for the paper-type GDL is obtained. [ABSTRACT FROM AUTHOR]

Technological advancements in flexible and wearable electronics have driven a boom in high-performance flexible electrodes. In this study, a simple and low-cost bio-inspired filter paper (FP) template method using the interfacial-aided polyethyleneimine-functionalized filter paper (FP-PEI) was developed to fabricate highly flexible silver-based conductive films. The FP was modified through amination to obtain FP-PEI with the rigid cellulose backbone and the flexible side chain of grafted amino groups, which played a key role as an interfacial layer during the chemical deposition of fractal-structured silver particles (FSSPs). The naturally porous and rough network structures of FP templates provided structural support and network for the deposition of conductive materials. In addition, the high porosity of FP facilitated the effective transfer of electrons, and its nano- or micro-scale rough surface structure promoted the formation of strong adhesion between the cellulose substrate and the conductive layer, which was crucial for the conductive stability of the device. The obtained conductive films (FP-PEI/FSSPs) exhibited a low sheet resistance of 1.47 Ω sq−1, a conductivity of 3401 S m−1, and good mechanical properties with a stress strength of 6.17 MPa. Moreover, FP-PEI/FSSPs exhibited a stable electrical conductivity (the sheet resistance only increased by 0.06 Ω sq–1 through 500 bending cycles), thermal stability (the maximum thermal decomposition rate increased from 349.3 to 357.8 °C), and oxidation resistance (the sheet resistance increased by only 0.04 Ω sq–1 after FP was exposed to the air for 15 days). The results indicate that FP-PEI/FSSP conductive films can be a potential green flexible electronic material. [ABSTRACT FROM AUTHOR]

The power transformer is a vital element in power system assets. When failure occurs in transformers, it leads to more revenue loss for the electrical utilities. Power transformer failures may occur due to high stresses on the insulating systems (oil and paper). These stresses categorize as electrical, thermal, and mechanical stresses. The main contribution of the current work is to increase the contribution of essential test parameters, which contribute to determining the insulating transformer state. In this work, principal component analysis (PCA) is not used as a prediction or classification tool. Still, it preserves only the necessary information and marginalizes or reduces the role of parameters with fewer contributions. PCA is a statistical method to compress an extensive data set of variables to a smaller number of orthogonal factors unrelated to interpreting the correlation matrix. One hundred forty-seven data samples were collected from the Saudi Electricity Company and used in this study. The data include the dissolved gas analysis (DGA) test, the breakdown voltage (BDV), moisture content (MC), Acidity (AC), interfacial tension (IFT), oil color (OC), dissipation factor (DF) or tan □, furan content (2-FAL). Based on PCA, some test variables can be selected as indicators for the insulating paper state from more test variables groups, reducing the cost of all tests. [ABSTRACT FROM AUTHOR]

Power transformers are critical equipment responsible for the transmission and transformation of electrical energy, and they are an important component of power system. Under the combined effects of electric field, thermal field, and mechanical stress, insulation degradation is prone to occur in oil-paper insulation structures. Among them, the "liquid-solid" interface formed by oil and oil-immersed pressboard is the weak point in transformer insulation, and extensive operational experience has shown that creeping flashover of insulating pressboard is a common fault in power transformers. Creeping flashover of insulating pressboard can rapidly destroy the insulation structure, leading to irreversible damage to the transformer and posing a serious risk of transformer accidents. In recent years, many scholars have conducted in-depth research on the characteristics and mechanisms of creeping flashover in oil-paper insulation structures using various experimental methods. They have obtained significant findings that have important theoretical and practical implications for optimizing the structure of power transformers and improving their reliability. This paper first introduces the characteristics of the electromagnetic environment inside the power transformer and the common forms of creeping flashover accidents in engineering. Then, classified according to the uneven degree of electric field and creepage distance of test electrodes used in relevant research, and the test methods and flashover characteristics of small size (<5 cm) and large size insulating pressboard under extremely uneven and slightly uneven electric fields are introduced respectively. Secondly, the existing breakdown model and mechanism theory of oil-paper insulation structure creeping flashover are summarized. Finally, the limitations of the existing creeping flashover test method of insulating pressboard are analysed, and the key issues to be solved are condensed. This review aims to provide readers with a comprehensive overview of the test methods, characteristics, and mechanisms of insulating pressboard creeping flashover. [ABSTRACT FROM AUTHOR]

During the folding process substrates are exposed to high-localized stresses, which in the case of coated papers and boards, can lead to decreased aesthetic features or complete loss of functionality. Production efficiency of the folding process could be improved by an automated, computer vision-based inspection system. For such a task, different existing computer-aided fold-crack evaluation approaches were analyzed. A detailed research was conducted to propose an image processing based fold cracking assessment via finding optimal sample preparation and digitization techniques and developing an algorithm for the digital image analysis and feature extraction. The analysis of the applicability of different sample preparation and digitization parameters, as well as the proposed digital image feature, was done by correlation evaluation, one-way analysis of variance (ANOVA) and corresponding post hoc tests. The results indicated that the developed algorithm fulfils the set requirements and the proposed feature of digitized samples faithfully describes the analyzed fold-cracks. [ABSTRACT FROM AUTHOR]

The condition and health of large oil-immersed power transformers' insulation have a direct impact on the safety and stability of the power grid. Therefore, it is crucial to investigate the aging characteristics of oil–paper insulation in power transformers. In this study, we developed a computational model for reclosing current calculation and multiphysics coupling models for magnetic-circuit-force, electrostatic field, and temperature field simulations. The calculated aging resulted in a mechanical stress of 8.71 MPa, an electric field strength of 2.26 × 106 V/m, and a temperature of 113.7 °C. We conducted combined electrical–thermal–mechanical aging tests on the oil–paper insulation and measured various insulating paper performance parameters at different aging stages. Our study revealed that both the mechanical and electrical properties of the insulating paper deteriorated in both aging groups. However, the changes were more pronounced in the electrical–thermal–mechanical aging group compared to the electrical–thermal aging group, indicating that mechanical stress accelerated the aging process of the insulating paper. In the early stages of aging, the rate of performance changes in the electrical–thermal aging group was similar to that in the electrical–thermal–mechanical aging group. However, as the aging time increased, the degradation of performance induced by mechanical aging became more significant. This suggests that the insulating paper's resistance to mechanical damage, specifically short-circuit resistance, noticeably decreased after prolonged aging. [ABSTRACT FROM AUTHOR]

The Alessandrina Library was founded in 1667 by pope Alexander VII Chigi and is nowadays housed in the Campus of Sapienza University of Rome (Italy). Within its Ancient (mostly made of rag paper) and Modern (mostly made of contemporary paper) collections, it includes more than one million books produced from the XVI to the XXI century. In 2019, six thermo-hygrometers were deployed in its multi-storey repository to monitor temperature (T) and relative humidity (RH). Hourly T and RH data collected over 2 years allowed us to evaluate spatial and temporal thermo-hygrometric distributions and to carry out a comprehensive assessment of the climate-induced risks (mechanical, chemical, and biological deterioration mechanisms). Vertical temperature gradients associated with unstable conditions occurred in winter, resulting in upraising air flows up to the ceiling. The risky short-term RH fluctuations (EN 15757:2010) were determined to avoid mechanical stress in case of loans, relocation, and consultation. The Time Weighted Expected Lifetime (TWEL) index was used to evaluate the chemical risk for different paper-based collections as a function of their acidity and degree of polymerisation, also considering the typical response time of paper books to T and RH changes. The TWEL calculation estimated that the durability of acidic paper was around 300 years and highlighted that rag paper could be subject to cellulose hydrolysis only in summer and autumn, while contemporary paper was mostly at no risk. The risk of mould germination (Sedlbauer diagram) was possible on few days in Autumn, while the production of insect eggs (Brimblecombe empirical function) was favoured during approximately 42% of time over the year. In addition, illuminance and colorimetric measurements (performed on selected book covers) showed that light-sensitive objects could be exposed to the photodeterioration risk in the east-facing side of the repository. Although the investigation focussed on a specific case study, a similar approach could be effectively adapted to most library and archival repositories conserving paper-based collections. [ABSTRACT FROM AUTHOR]

The Journal of Materials Science awards the annual Robert W. Cahn Prize to recognize the best paper published in the journal each year. The winner of the 2023 Cahn Prize is a research paper titled "Molecular modelling of graphene nanoribbons on the effect of porosity and oxidation on the mechanical and thermal properties." The paper presents molecular simulation models of graphene nanoribbons and examines the impact of porosity and oxidation on their mechanical and thermal conductivity properties. The paper is well-written and provides valuable insights for researchers in this field. Two other papers were selected as runners-up for the prize. All the monthly finalists for the Cahn Prize can be downloaded for free on the journal's website. [Extracted from the article]

Strain sensors which are embeded in AMOLED are introduced and studied in this paper. High accuray strain sensing are achieved, resolution of the sensors are about 0.05%. By combing the strain sensors in the panel, mechanical behaviors can be monitored and studied in real time. The snesors are used to conduct the foldable AMOLED mechanical and reliability study. Dynamic and static strains and related mechanism are introduced and discussed. Finite element simulation models considering the mechanical properties of materials including hyperelasticity, viscoelasticity and creep are established. Finally, the strain sensors and finite element anlysis are combined to study the mechanical response of AMOLED under dynamic folding, static folding, and different temperature and humidity environments. [ABSTRACT FROM AUTHOR]

In this work, we present a methodology to assess wrist pressure during the handwriting process. Using optical coherence tomography, it was possible to determine the deformation suffered by the paper during the handwriting process. A calibration of the deformation suffered by the paper as a function of the pressure exerted by the pen was performed, making it possible to determine several parameters of interest, such as the radius of the pen tip sphere R = 488 ± 2 ¡im, the Poisson coefficient v = 0.30 ± 0.02 and the effective Young's modulus of bond paper 75 g/m2. To this end, we developed a method for determining the Hooke modulus for a spring, with which we built a device for applying a known force to a ballpoint pen during the handwriting process. We also performed the study depending on the type of substrate, with five volunteers trying to copy the same signature on four different types of paper. Using the optical coherence tomography technique, we demonstrate that it is possible to differentiate the authorship of a signature also by the depth of deformation on the paper. The experimental procedure also made it possible to determine the Poisson's coefficient and determine the effective Young's Modulus of the paper. [ABSTRACT FROM AUTHOR]

The article analyses the effects of paper moisture content on energy absorbed during its tensile testing in the range of moisture equilibrium obtained during paper air conditioning at a temperature of 23 °C. To predict changes in breaking energy caused by changes in moisture content, two calculation methods were proposed. The methods were verified on the basis of laboratory tests and calculation results, and their practical usefulness was confirmed. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical properties of nano-silica modified insulating paper under the combined action of mechanical vibration and temperature conditions are studied. Unmodified and nano-silica modified cellulose insulating paper with 2 wt% and 4 wt% were prepared, respectively, and a series of mechanical-thermal synergy experiments were carried out. With the same mechanical stress and temperature, and with the same aging duration of 144 h (6d), the tensile strength of modified insulating paper with 4 wt% nano-silica, increased 0.99 kN/m and 0.55 kN/m, respectively, compared with those of the unmodified and the 2 wt% nano-silica modified insulating paper. The experiments indicate that the nano-silica modification can effectively improve the mechanical properties of insulating paper. In this work, the modified mechanism of nano-silica is analyzed from the interface effect of modified polymer and the quantum effect of the modified polymer interface two aspects. It is shown that the interface formed in the modified insulating paper can transfer the mechanical stress acted on the insulating paper and prevent the cracks formed in the aging process of the test sample from further expansion, while the quantum effect discretizes the electron energy level, which can restrict the motion of the molecular chain segment to some extent. The conclusion can be used for reference to improve the performance of insulating paper. [ABSTRACT FROM AUTHOR]

The article discusses the modeling of bagginess subject to stress relaxation during storage in paper reels with ridges. Information on creep tests and relaxation tests is presented. Charts depicting construction of isometric creep curves, curve-fitting constants and machine direction tensile properties for paper grades, and diagrams depicting the load with strain and time are presented. Results show that runnability problems may appear if the ridge height is small and may occur in actual reels.

Copyright of Fibres & Textiles in Eastern Europe is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research work presents a method for the determination of the limit of elasticity of paper considered as a variable dependent on stress and the time of its duration. For plane stress it was found that in the case of a low share of permanent strain in the total strain, we can assume that the highest value of its share appears on one of the principal axes of stress. Such an assumption allowed to use a one-dimensional rheological model to define the permanent range in a two dimensional state of stresses for paper. [ABSTRACT FROM AUTHOR]

Abstract: The growth of molds on paper containing cellulose is a frequent occurrence when the level of relative air humidity is high or when books become wet due to water leaks in libraries. The aim of this study is to differentiate the bioreceptivity of different types of book paper for different fungi. Laboratory tests were performed with strains of Aspergillus niger, Cladosporium sp., Chaetomium globosum and Trichoderma harzianum isolated from books. Four paper types were evaluated: couché, Pólen (offset), recycled and a reference paper containing only cellulose. The tests were carried out in chambers with relative air humidity of 95% and 100%. Mold growth was greatest in the tests at 100% relative humidity. Results of stereoscopic microscopy observation showed that Cladosporium sp. grew in 74% of these samples, A. niger in 75%, T. harzianum in 72% and C. globosum in 60%. In the chambers with 95% air humidity Cladosporium sp. grew in only 9% of the samples, A. niger in 1%, T. harzianum in 3% and C. globosum did not grow in any sample. The most bioreceptive paper was couché and the least receptive was recycled paper. The composition of the recycled paper, however, varies depending on the types of waste materials used to make it. [Copyright &y& Elsevier]

Plastic concrete is a kind of flexible concrete cutoff wall material, which is used to solve the problem of poor coordinated deformation ability between ordinary concrete cutoff wall and surrounding soil. It has the characteristics of small elastic modulus and large limit strain, which greatly improves the operation condition of cutoff wall. In order to save bentonite resources and recycle waste automobile tires, this paper crushed waste automobile tires into rubber particles and mixed them into plastic concrete, through the uniaxial compression test and triaxial compression test, obtained the corresponding stress–strain curve, rubberized plastic concrete strength and deformation properties are studied and the rubber particles and the relationship between dosage. The test results show that the compressive strength of rubberized plastic concrete decreases with the increase of rubber particles content, but the deformation capacity increases with the increase of rubber particles content. In this paper, the regression analysis of rubberized plastic concrete constitutive relation and failure criterion including the influence factor of rubber particles are helpful to promote the engineering application of rubberized plastic concrete and reduce the exploitation of natural resources and environmental pollution. [ABSTRACT FROM AUTHOR]

Earthquakes nucleate when large amounts of elastic energy, stored in the earth's crust, are suddenly released due to abrupt sliding over a fault. Fluid injections can reactivate existing seismogenic faults and induce/trigger earthquakes by increasing fluid pressure. Here we develop an analogous experimental system of simultaneously loaded and wetted absorbent porous paper to quantify theoretically the process of wetting‐induced earthquakes. This strategy allows us to gradually release the stored energy by provoking low intensity tremors. We identify the key parameters that control the outcome of the applied injection strategy, which include the initial stress state, fault segmentation, and segment‐activation rate. Subsequent injections, initiated at high stress levels, can drive the system faster toward its instability point, nucleating a large earthquake. Starting at low stress levels, however, they can reduce the magnitude of the natural event by at least one unit. Plain Language Summary: Understanding natural and anthropogenic seismicity is a major scientific challenge. Here we present a novel analogue fault model using absorbent porous paper, which gives new insights on earthquake mitigation. When scaled to in‐situ conditions, the porous paper model represents a natural seismic rupture of magnitude Mw = 5.9. By progressively wetting it, we simulate fluid injections in the earth's crust and draw analogies to large‐scale industrial projects. In our experiments, each injection is accompanied by tremors, which progressively release energy and modify the energy budget of the system. Without precise knowledge of the fault properties, we risk driving the system faster toward an unexpected large seismic event. However, provided that the model's key parameters–fault segmentation, segment‐activation rate, and stress state–are well known or controlled, the natural rupture can be mitigated by at least one unit. We expect that these results will facilitate risk reduction in current fluid injection projects and inspire earthquake mitigation strategies for real tectonic faults. Key Points: From an energetic point of view, absorbent porous paper can be an ideal, low‐cost surrogate rock material for studying induced seismicitySegmentation of faults and sequential fluid injection in each segment can mitigate potential earthquakes by at least one order of magnitudeWe show that fault segmentation, segment‐activation rate and stress state predominantly control the result of applied injection strategies [ABSTRACT FROM AUTHOR]

Stochastic two-dimensional elastic–plastic network models are used to represent the inelastic deformation behavior of well-bonded paper. Linear kinematic hardening is employed with an initial non-zero back stress to represent anisotropic fiber yield. Network models are used to simulate simple monotonic tension and simple cyclic tension of paper materials. The performance of the models is compared to experimental results and found to perform reasonably well. The results suggest that interfiber bonding must be explicitly accounted for to adequately describe the material. Some discrepancy between the model and experimental cyclic tension results is believed to be due to time-dependent strain recovery in the material which is not represented in the network models. Experimental results are also presented which show that simple tension failure in these materials occurs along a line of localized deformation in a majority of the samples. This line is generally observed to form immediately prior to failure and is oriented at a well-defined angle with respect to the loading direction. [Copyright &y& Elsevier]

A spongy graphene paper with an inside foldable corrugated structure is fabricated by electrothermal reduction of the oxygen-containing groups inside an RGO paper. Reversible macroscopical length contraction of the spongy graphene paper with a strain of 2.4% under 10 V voltage is exhibited, mostly attributed to the deformation of corrugated structures. [ABSTRACT FROM AUTHOR]

In South Africa, a major initiative to encourage load shifting and reduce strain on the electricity grid prompted one paper mill to investigate the pumping processes at its water supply plant. In this detailed two-part case study, Graeme Harding takes us through the investigative process leading to the final solution, which has yielded a 25% energy saving since implementation. [ABSTRACT FROM AUTHOR]

The dynamic mechanical properties of coated offset paper before and after application of isopropyl alcohol and surfactant solutions have been investigated. The mechanical properties of the papers were studied with dynamical mechanical analysis in the tensile mode and the samples were submitted to a uniaxial loading in stress-strain measurements. An increase in the isopropyl alcohol concentration slightly reduced the mechanical strength, while the addition of surfactant clearly made the paper stiffer and weakened the paper strength. As the surface tensions of the liquids were adjusted to the same level, the changes in mechanical properties are ascribed to changes in water-induced wetting and subsequent changes in interfacial properties within the paper constituents. The storage and loss moduli of the paper after application of the surfactant solutions were twice those recorded after isopropyl alcohol treatment. The binder was not affected by the solutions, but there was significant debonding, disrupting the internal or surface structure in the base paper-coating layer interface, especially by surfactant solutions. [ABSTRACT FROM AUTHOR]

Graphene paper (GP) has been prepared by flow-directed assembly of graphene nanosheets. The mechanical properties of as-prepared GPs were investigated by tensile, indentation, and bending tests. Heat treated GPs demonstrate superior hardness, ten times that of synthetic graphite, and two times that of carbon steel; besides, their yielding strength is significantly higher than that of carbon steel. GPs show extremely high modulus of elasticity during bending test; in the range of a few terapascal. The high strength and stiffness of GP is ascribed to the interlocking-tile microstructure of individual graphene nanosheets in the paper. These outstanding mechanical properties of GPs could lead to a wide range of engineering applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Imidazole based AIE active molecular probe is synthesised. • The probe, weakly emissive in solution, exhibits excellent solid state emission. • In solid state, the probe exhibits reversible mechanochromism and acidochromism. • The mechanochromic property is employed to fabricate the rewritable papers. • Acidochromism is demonstrated on paper strips for use in real sample analysis. Stimuli modulated fluorescence properties of imidazole-based molecular probe (E)-2-(5,5-dimethyl-3-(4-(1,4,5-triphenyl-1H-imidazole-2-yl)styryl)cyclohex-2-en-1- ylidene)malononitrile (Ph-ISO) in the solid state is presented. Not only did the probe display aggregation induced emission (AIE) activity with intense solid-state fluorescence emission, but also exhibited several repetitive cycles of reversible mechanochromism as well as acidochromism. The solid-state emission is ascribed to the intermolecular interactions in the highly twisted conformation of Ph-ISO via multiple C–H---N and C–H---π interactions as confirmed by the single crystal X-ray analysis. The applied mechanical stress in the form of grinding results in the transformation of crystalline state to the amorphous state with a red shifted emission band attributed to attaining more planar conformation vs twisted conformation, with extended molecular conjugation. While reversible mechanochromism makes the probe suitable for rewritable papers, the switchable acidochromism is useful for the on-site monitoring of pH differences in biological and environmental media. [ABSTRACT FROM AUTHOR]

Studies of voltage-induced deflections in electroactive paper (EAPap) have been carried out. On the experimental side, measurements of bias-dependent deflections and strain, water absorption as a function of time, and relative humidity were obtained for the cellulose EAPap actuator. In addition, model simulations have also been carried out to probe and quantify the role of the various internal mechanisms responsible for the deflection. Our simulation predictions yield good agreement with the measured deflection data for the EAPap. The modeling suggests that internal ion content and its migration, water absorption leading to a nonuniform permittivity, random variations in the transverse piezoelectric-coupling coefficient d31,i, and the modulus of elasticity all collectively contribute to the EAPap deflection electrophysics. It also appears that higher sensitivity, with a minimal bias dependence, could be achieved by deliberately adding ions during EAPap processing. [ABSTRACT FROM AUTHOR]

Cellulose paper is considered to be a promising substrate of energy materials for energy storage device due to its flexible, porous, renewable, degradable, and environmental-friendly feature. However, the large weight and low conductivity of cellulose fibers limit the specific capacitance and energy density of the paper electrodes. Converting cellulose fibers into conductive carbon fibers (CCF) by high temperature carbonization is an effective strategy for improving the electrochemical performance of paper electrodes. But the brittleness of carbonized paper limits its application in flexible supercapacitors. In addition, stable loading of energy materials on CCF is another challenge. Here, KNO 3 in-situ etching activation method is used to construct the embedded structure of transition-metal oxides (TMOs) on CCF. And the embedding degree of TMOs on CCF can be adjusted by controlling the amount of KNO 3. The embedded structure releases the mechanical stress from bending of CCF, endowing good flexibility for carbonized paper. In addition, embedded structure can anchor TMOs into CCF, and increase the porosity and specific surface area of CCF, promoting a rapid ion diffusion and electron transport for high capacitance contributions. The KNO 3 -etched Co 3 O 4 @CCF paper as an electrode exhibits a high volume specific capacitance of 72.3 F cm−3 at current density of 0.5 mA cm−2 (more than three times higher than that of Co 3 O 4 /CCF paper) and shows good rate capability (capacitance retention of 83.3% with 10 times current density) and long lifetime (charge-discharge stability of 94.8% after 10000 cycles). Even in bending state, the composite paper still maintains stable electrochemical performances, which can broaden potential application in flexible supercapacitors. [Display omitted] • A flexible carbonized paper was fabricated for supercapacitors electrode. • KNO 3 in-situ etching activation method was used to embed TMOs into CCF. • The embedded structure released the mechanical stress from bending of CCF. • The embedded structure increased the porosity of CCF for rapid ion diffusion. • The flexible carbonized paper exhibited excellent electrochemical performances. [ABSTRACT FROM AUTHOR]

In this article the author outlines his understanding of self-psychology as an independent psychoanalytic treatment paradigm created by the late Heinz Kohut and initially geared toward the psychoanalytic treatment of narcissistic disorders. Since then, self-psychology theory and practice have been enriched by new theoretical and clinical considerations and have been introduced into other forms of psychotherapy, counseling, and education, for example. One important conceptual contribution to developmental theory was Heinz Kohut's differentiation of separate narcissistic and "object love" related developmental tasks. Today, new paradigms as i.e. relational analysis stress the value of human relationships and of the value of mutual recognition. This warrants a revisiting of the clinical value of the self-psychological understanding of narcissism. According to the author it lies in the nature of unattended narcissistic needs that when unattended they take primacy over relational aspects and demand adequate attention in order to open up the space for mutuality, reciprocity et cetera. [ABSTRACT FROM AUTHOR]

To model advanced 3-D forming strategies for paper materials, the effects of environmental conditions on the mechanical behavior must be quantitatively and qualitatively understood. A tensile test method has been created, verified, and implemented to test paper at various moisture content and temperature levels. Testing results for one type of paper for moisture contents from 6.9 to 13.8 percent and temperatures from 23 to 168 degrees Celsius are presented and discussed. Coupled moisture and temperature effects have been discovered for maximum stress. Uncoupled effects have been discovered for elastic modulus, tangent modulus, hardening modulus, strain at break, tensile energy absorption (TEA), and approximate plastic strain. A hyperbolic tangent function is also utilized which captures the entire one-dimensional stress-strain response of paper. The effects of moisture and temperature on the three coefficients in the hyperbolic tangent function may be assumed to be uncoupled, which may simplify the development of moisture- and temperature-dependent constitutive models. All parameters were affected by both moisture and temperature with the exception of TEA, which was found to only be significantly dependent on temperature. [ABSTRACT FROM AUTHOR]

Mechanical fields over thin elastic surfaces can develop singularities at isolated points and curves in response to constrained deformations (e.g., crumpling and folding of paper), singular body forces and couples, distributions of isolated defects (e.g., dislocations and disclinations), and singular metric anomaly fields (e.g., growth and thermal strains). With such concerns as our motivation, we model thin elastic surfaces as von Kármán plates and generalize the classical von Kármán equations, which are restricted to smooth fields, to fields which are piecewise smooth, and can possibly concentrate at singular curves, in addition to being singular at isolated points. The inhomogeneous sources to the von Kármán equations, given in terms of plastic strains, defect induced incompatibility, and body forces, are likewise allowed to be singular at isolated points and curves in the domain. The generalized framework is used to discuss the singular nature of deformation and stress arising due to conical deformations, folds, and folds terminating at a singular point. [ABSTRACT FROM AUTHOR]

Focuses on operational issues in high-speed curtain coating of paper. Emergence of curtain coating as a new coating process for specialty and printing paper grades and for paperboard; Method that features a liquid sheet that falls freely before imprinting onto the moving paper web to be coated; Benefits of non-contact coating method in minimizing web breaks due to the absence of mechanical stresses onto the substrate to be coated.

This study investigates the effect of paper sludge's mixing ratio and the types and concentrations of coupling agents on the physical and mechanical properties of paper sludge—thermoplastic polymer composites. In the experiment, four levels of mixing ratios of paper sludge to thermoplastic polymer (10:90, 20:80, 30:70 and 40:60) and three levels of coupling agent (Epolene G-3003™) content (1, 3, and 5wt.%) were designed to discuss the physical and mechanical properties of composite. Composite density, as expected, increased but melt flow index decreased when the paper sludge content increased. Thickness swelling and water absorption of composites was slightly improved by the addition of paper sludge compared with control specimens. Tensile properties of composites significantly increased as the mixing ratio of paper sludge increased. Especially, tensile modulus improved with the increase of paper sludge content. Flexural strength and modulus showed similar trends to that of the tensile properties. Notched and unnotched Izod impact strengths lowered by the addition of paper sludge. With the addition of coupling agent, G-3003™, tensile and flexural properties improved considerably compared with control specimens (without any coupling agent). Epolene G-3003™, with high molecular weight, was effective in the improvement of the composites' tensile and flexural properties. [ABSTRACT FROM AUTHOR]

Abstract: Dynamic mechanical analysis combined with relative humidity (DMA-RH) was used to examine the viscoelastic properties of standard Kraft and extensible Clupak paper in dry and humid atmosphere. Knowledge regarding these viscoelastic properties combined with the natural hygroscopicity of paper is fundamental for the prediction of paper behaviour under stress conditions. Results from DMA-RH under dynamic (frequency/strain experiments) and static measurement modes (creep/recovery experiments) indicated that the change of paper structure during the Clupak process is significant. Marked changes in elongation and stiffness as well as relaxation ability of Clupak paper were found. DMA-RH allows the combining multiple conditions (frequency, temperature, time, load, and humidity) during a single measurement and it can thus simulate similar conditions to those in paper processing and product-use. [Copyright &y& Elsevier]

Copyright of Teknoloji is the property of Engineering Science & Technology, an International Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The in-plane shear strengths (IPSS) of copy paper, filter paper, and sack paper were obtained from an asymmetric four-point bending (AFPB) test. Rectangular tabs of medium-density fibreboard (MDF) were bonded to the paper specimen. The length of the clearance between the tabs was varied, and the influence of the clearance on the IPSS value was investigated. The IPSS obtained from the AFPB test was compared with that obtained from a 35° off-axis tension (OAT) test, which was proposed in a previous study. The IPSS values obtained from the AFPB tests on the copy paper and sack paper were significantly lower than those obtained from the 35° OAT tests because of the localised buckling caused by the negative principal stress. In contrast, the IPSS values obtained from the AFPB and OAT tests on the filter paper were in agreement when the clearance length was >5 mm because the buckling effect was excluded. [ABSTRACT FROM AUTHOR]

Summary The quality of a wound roll is highly dependent upon the in-roll stress distribution, which is controlled by the operating parameters of the center-wind torque, nip and tension. With increasing demands for higher performance of paper winding systems in terms of higher winding speeds, wider web widths and larger wound roll diameters, it becomes of vital importance to determine and understand the optimum operating conditions of these machines. In this paper, a numerical formulation for estimating the in-roll stress of a wound roll is proposed with taking account of the effect of nonlinearity in web compressibility, air-entrainment and permeance. The in-roll stress is calculated as the superposition of the stress increments caused by each winding. The theory of elasto-hydrodynamic lubrication with the compressibility of air is introduced to evaluate the effect of air-entrainment at the roll-inlet. Permeance of air is newly incorporated into the winding model, which is expressed under the assumption that permeance is proportional to the pressure difference of both sides of a web. In order to assure the applicability of the proposed theory, winding tests were conducted using the dry-end section of the paper-making pilot machine. The numerical analysis and experimental observation show the significant effect of the air-entrainment and permeance upon the in-roll stress. [ABSTRACT FROM AUTHOR]

Conventional wearable electronics do not have conformal contact with the skin, so they might produce unreliable detecting of physiological signals during continuous health monitoring. This leads to the skin‐like healthcare patch that ensure secure contact with skin and maximizes user's comfort during daily life. Here, we present skin‐like stretchable and conformable healthcare patch in which stretchable organic light‐emitting diode (OLED) matrix display and a stretchable organic photoplethysmography (PPG) sensor are implemented together. The patch, fabricated on elastomer substrate without pre‐strained fabricating process, maintain stable operation up to 30% strain by the use of the stress relief layers and deformable micro‐cracked interconnects that reduce the mechanical stress of the OLED matrix display and PPG sensor. The simple device structure and reliable fabrication process show promise for commercialization of healthcare patch as novel form‐factor of wearable electronics. [ABSTRACT FROM AUTHOR]

Studies the strength of periodic press section marks in paper by researchers from Great Britain. Parameters that influence the degree of felt marking; Development of new technique that can predict the degree of felt marking quantitatively; Usability of pressure-sensitive material to measure the distribution of loads arising from the fabric's structure when the applied load is constant.

This document discusses a research paper that explores the effects of relative density and particle morphology on the bearing capacity and collapse mechanism of strip footings in sand. The authors observe the development of shear zones during loading and question the behavior of two different sands tested in the study. They also discuss the combined effects of relative density and particle morphology on shear resistance. The document provides valuable insights and suggests further areas of investigation. The article concludes that relative density is not the primary factor influencing performance and suggests using laboratory strength tests to evaluate the effects of various factors on effective friction angles. The data from the study and previous research indicate that correlations between relative density and bearing capacity are not reliable for sands other than those studied. Instead, a more fundamental approach involves correlating foundation performance with mobilized effective friction angles. [Extracted from the article]

Mechanical fields over thin elastic surfaces can develop singularities at isolated points and curves in response to constrained deformations (e.g., crumpling and folding of paper), singular body forces and couples, distributions of isolated defects (e.g., dislocations and disclinations), and singular metric anomaly fields (e.g., growth and thermal strains). With such concerns as our motivation, we model thin elastic surfaces as von Kármán plates and generalize the classical von Kármán equations, which are restricted to smooth fields, to fields which are piecewise smooth, and can possibly concentrate at singular curves, in addition to being singular at isolated points. The inhomogeneous sources to the von Kármán equations, given in terms of plastic strains, defect induced incompatibility, and body forces, are likewise allowed to be singular at isolated points and curves in the domain. The generalized framework is used to discuss the singular nature of deformation and stress arising due to conical deformations, folds, and folds terminating at a singular point. [ABSTRACT FROM AUTHOR]

Impact of maintenance conditions upon the paper resistance was investigated. Dependencies of tensile strength and resistance to bending of different paper type on paper fibers direction and humidity were presented. [ABSTRACT FROM AUTHOR]

We have performed bias-stress measurements and determined the shelf-life of environmentally friendly paper electronic devices. We have utilized a low-voltage transistor that has a sorbitol-based ionic liquid as the electrolyte and a blend of poly(3-hexylthiophene) and poly( l-lactic acid) as the semiconductor layer. The bias-stress measurements revealed that the devices operated below 1V are functioning without degradation, while above 1V an irreversible degradation process, probably due to water-induced oxidation of the semiconductor. A number of these devices are then used to create more complicated logic with, that is the operation of a NOR-gate and a one bit memory is demonstrated. A D-latch manufactured on paper connected on a breadboard using a sample containing five paper transistors and three resistors. [ABSTRACT FROM AUTHOR]

In operation, the insulation paper used for transformers is subject to electric stress. This paper may deteriorate as a result of the accumulation of mechanical stress and the polarisation of the electric field. The effect of electric fields on insulation paper is typically investigated through macroscopic tests; thus, the microscopic mechanism must be explored further. In this study, single- and multi-chain cellulose models were constructed to simulate the yield behaviour of cellulose under a strong electric field (1010 V m− 1) through molecular dynamics. The cracking process of insulation paper was also examined according to density functional theory. Results indicated that both single- and multi-chain celluloses yield under a strong electric field. This yield behaviour is consistent with that of the electric field, and it eventually breaks the cellulose chains. The energy gap between the lowest unoccupied and the highest occupied molecular orbitals suggested that cellulose molecules may encounter insulation breakdown at an electric field strength of 105 V m− 1. Furthermore, the initial fracture in the molecular chain of cellulose was observed under the weakest glycosidic bond. [ABSTRACT FROM PUBLISHER]

The mechanical behavior of two packaging paper materials subjected to tensile loading up to complete breakage has been investigated. A model for isotropic strain hardening elastic anisotropic plasticity, coupled to anisotropic damage, is discussed. The constitutive relations, including a gradient enhanced damage model, are developed within a thermodynamical framework. The Helmholtz free energy in the continuum is assumed to depend not only on the strain and stress components but also on the damage in the material.The model has been analyzed in a non-linear finite element procedure. The capability of the model to properly capture and simulate the failure of a paper material subjected to tensile loading is demonstrated by means of several numerical examples that are compared to, and verified with, experiments on packaging paper specimens of varying geometry. [Copyright &y& Elsevier]

ABSTRACT: We reformulate the original model of Hatchell and Bourne and Røste, Stovas and Landrø that couples fractional velocity change to subsurface strain via a fundamental constant R. The new model combines elastic compressibility of a dual‐porosity system for a sand–shale mixture with horizontal planes of inter‐granular weakness. The majority of observed R‐factor magnitudes from post‐stack 4D seismic data in both the reservoir and overburden can thus be explained. R is predicted to depend strongly on lithology and also initial strain state. The model is also extended to predict the observed angle‐dependence of time‐lapse time‐shifts from pre‐stack data. An expression for the gradient of time‐shift with incidence angle is obtained in terms of the background VP/VS, and also the ratio of tangential to normal compliances BT/BN representing loss or creation of inter‐granular coupling. If accurately estimated from data, this compliance ratio can be used as an additional parameter to assess the post‐production state of the overburden. It is concluded that whilst R remains the over‐arching parameter controlling the magnitude of time‐shifts measured from 4D seismic data, BT/BN is a subtler parameter that may also prove of future value. [ABSTRACT FROM AUTHOR]

A Conductor on Round Core (CORC) cable wound with a high-temperature superconductor is an important cable concept for high-current density applications. It is widely used in large power systems because of its advantages of good flexibility and high engineering current density. However, the complex design structure of CORC cable makes it very difficult to understand its electromagnetic properties (such as AC loss). In particular, the different winding directions of each layer in multi-layer cable have a great influence on its electromagnetic characteristics. In this paper, the H-method is used to solve the electromagnetism and mechanics equations. The influence of the winding direction of CORC cable on its electromagnetic field distribution characteristics, AC loss, and mechanical variation under the action of external magnetic field is investigated. The AC loss study of single-layer cable reveals that when the applied magnetic field is increased from 0.01 to 0.02 and 0.03 T, the AC loss peak of the cable increases by 107 and 103 orders of magnitude, respectively, indicating that the effect of low applied magnetic field on the AC loss of the cable is more significant. For multi-layer cables, cables with opposite winding directions have a greater depth of current density penetration than cables with the same winding direction. In addition, the mechanical variations of multi-layer cables with different winding orientations are explored. The results show that the Mises stress in the cable with the same winding direction is about 32% higher than that of the cable with the opposite winding direction, which indicates that the method of winding the cable in the opposite direction between adjacent layers of tape can avoid excessive mechanical stress. [ABSTRACT FROM AUTHOR]

Orthodontic archwire rotation around its long axis, known as third-order torque, is utilised to correct tooth rotational misalignments moving the tooth root closer to or away from the cheek through engagement with an orthodontic bracket. Studying the behaviour of archwire and brackets during an applied rotation can aid in better understanding and appreciating the mechanics of third-order torque, potentially allowing for more effective orthodontic treatment protocols. Mechanically characterising archwire behaviour during third-order torque application is a complex task due to their physical scale and geometries. An advanced measurement technique was needed to address these constraints. A three-dimensional (3D) non-contact optical method using a digital image correlation (DIC) system was developed. An orthodontic torque simulator (OTS) was used to apply and measure third-order torque with 0.483 × 0.635 mm (0.019″ x 0.025″) rectangular archwires in tandem with a 3D DIC system, whereby surface deformations and strains could be computed using correlation algorithms. The 3D DIC system was implemented to enable third-order torque experimentation with the OTS while imaging the archwire and bracket surfaces. The 3D DIC system's ability to measure 3D archwire deformations and strains was verified using a finite element model, where comparisons between 3D DIC measurements and calculated results from the model were made to ensure the measurement capabilities of 3D DIC in the context of third-order torque. The 3D DIC system was then used to compare archwire behaviour between stainless steel (SS) and titanium molybdenum alloy (TMA) archwires to study potential clinical differences in archwire behaviour, in which the archwires were rotated with a custom SS rigid dowel (RD) as well as commercial Damon Q orthodontic brackets. The quantification of third-order torque and archwire deformations and strains led to the conclusion that SS archwires led to larger torque magnitudes compared to TMA archwires. The RD resulted in larger archwire strains compared to Damon Q brackets. The 3D DIC system provides a non-contact measurement technique that can further be used with third-order torque experimentation with the OTS. Image 1 • Isolated orthodontic archwire response to torsion is studied. • Finite element analysis is used to verify optical measurements. • Three-dimensional digital image correlation strain measurement method is validated. • Stainless steel and titanium molybdenum alloy archwire responses are compared. • Three-dimensional orthodontic archwire and bracket strain measurements are obtained. [ABSTRACT FROM AUTHOR]

The hot spot temperature inside the windings of the oil-immersed power transformers may exceed 200 °C due to some winding deficiencies, posing negative impact on the paper insulation. A series of heating experiments are deliberately conducted with oil-paper insulation samples to study the influence of the hot spot temperature ranging from 120 to 280 °C, and the insulation degradation is characterized by the breakdown voltage (BDV) and the degree of polymerization (DP). Furthermore, surface morphology, water content and cellulose degradation mechanism are analyzed so as to reveal the causes of the above phenomena. The experimental results indicate that with increase of the hot spot temperature, the breakdown voltage increases after the first drop, while the DP continues to decline in the tested temperature range. No obvious linear relationship is observed between the hot spot temperature and the DP or the BDV. Regarding the test samples the authors have studied, the inflection point of the hot spot temperature for the insulation deterioration is found to be between 240 and 260 °C. The proposed research presents a fundamental reference for assessment of the winding insulation degradation from the viewpoint of hot spot temperature. [ABSTRACT FROM AUTHOR]

Folding of coated paper is examined numerically using the finite element method. Particular emphasis is put on the behaviour of field variables relevant for cracking of the coating layers. In the numerical analysis, the basepaper is modelled as an anisotropic elastic–plastic material (both elastic and plastic anisotropy is accounted for) while the constitutive behaviour of the coating layers are approximated by classical (Mises) elastoplasticity. The numerical results suggest, among other things, that particular forms of plastic anisotropy can substantially reduce the maximum strain levels in the coating. It is also shown that delamination buckling, in the present circumstances, will have a very small influence on the strain levels in the coating layer subjected to high tensile loading. [Copyright &y& Elsevier]

In a series of papers which are either published [Hadjesfandiari, A., Dargush, G. F., 2011a. Couple stress theory for solids. Int. J. Solids Struct. 48 (18), 2496–2510; Hadjesfandiari, A., Dargush, G. F., 2013. Fundamental solutions for isotropic size-dependent couple stress elasticity. Int. J. Solids Struct. 50 (9), 1253–1265.] or available as preprints [Hadjesfandiari, A., Dargush, G. F., 2010. Polar continuum mechanics. Preprint arXiv:1009.3252; Hadjesfandiari, A. R., Dargush, G. F., 2011b. Couple stress theory for solids. Int. J. Solids Struct. 48, 2496–2510; Hadjesfandiari, A. R., 2013. On the skew-symmetric character of the couple-stress tensor. Preprint arXiv:1303.3569; Hadjesfandiari, A. R., Dargush, G. F., 2015a. Evolution of generalized couple-stress continuum theories: a critical analysis. Preprint arXiv:1501.03112; Hadjesfandiari, A. R., Dargush, G. F., 2015b. Foundations of consistent couple stress theory. Preprint arXiv:1509.06299] Hadjesfandiari and Dargush have reconsidered the linear indeterminate couple stress model. They are postulating a certain physically plausible split in the virtual work principle. Based on this postulate they claim that the second-order couple stress tensor must always be skew-symmetric. Since they do not consider that the set of boundary conditions intervening in the virtual work principle is not unique, their statement is not tenable and leads to some misunderstandings in the indeterminate couple stress model. This is shown by specifying their development to the isotropic case. However, their choice of constitutive parameters is mathematically possible and we show that it still yields a well-posed boundary value problem. [ABSTRACT FROM AUTHOR]