Search

A comparison between uncreped and creped handsheets was performed to study the effect of fiber morphology and creping process on fiber web structure and tissue properties. Four wood and non-wood pulps refined at different levels were used to manufacture uncreped and creped handsheets using a creping simulator. A characterization of the fiber web structure using scanning electron microscopy (SEM) and evaluation of tissue properties (e.g. tensile strength, water absorbency, softness) was performed on the uncreped and creped handsheets. The results obtained with the creping simulator were compared with commercial products to evaluate the significance of the creping simulator results. The SEM images of the fiber web structure showed that the creping process promoted buckling and distortion of fibers, delamination of surface fiber layer, development of free fiber ends and creation of crepe folds, which enhanced water absorbency and softness at the expense of reduced tensile strength. Short and thin fibers seemed to be more effectively creped than long and coarse fibers. Long and coarse fibers seemed to offer higher resistance to the compressive forces acting at the creping blade. A reasonable correlation between the performance of uncreped and creped handsheets made with different fibers was observed. The results indicate that the performance of uncreped handsheets can be used as a semi-quantitative indication of the performance of creped handsheets. The performance of the creped handsheets were similar to commercial products, which indicates that the creping simulator can be used as an alternative to study the creping process at laboratory scale. [ABSTRACT FROM AUTHOR]

Experimental tests of a seven-bolted connection with an asymmetric contact area between the joined elements are presented. The research is divided into two stages. In the first one, the connection is preloaded in a three-pass cycle. In the second stage, the connection is loaded with a monotonic alternating force applied at an angle of 30 degrees to the contact surface of the joined elements to generate compressive and shear forces in the connection. The tests are carried out with the use of the INSTRON 8850 testing machine. As a result, the courses of forces in the bolts measured with the use of resistance strain gauges and the relative displacements between the joined elements measured with an extensometer are shown. In the second part, the modeling of the connection in the convention of the finite element method is presented. The joined elements are modeled with the use of spatial finite elements, and the fasteners, as the hybrid elements made of deformable beams, rigid heads, and rigid nuts. The paper is completed with a comparison of the results obtained from the measurements and calculations, based on which the conclusions important from the point of view of the FEM analysis are drawn. [ABSTRACT FROM AUTHOR]

Disassembly is the first step in the remanufacturing of a product. This paper presents the design of a robot end-of-arm tool for removing a peg from a hole, a common operation in the disassembly of mechanical products. The device is a compliant structure that enables the peg to be pulled out of a closely fitting hole without jamming or wedging. The device is reminiscent of the Remote Centre Compliance (RCC) mechanism used by assembly robots to insert cylindrical pegs into cylindrical holes with small clearances. However, whereas the RCC mechanism has primarily to withstand compressive forces, the proposed compliant device must resist tensile forces because of the nature of disassembly operations. The paper details a finite-element modelling study of peg removal with and without using the compliant structure. The results obtained show that the structure markedly reduces the stresses at the points of contact between the peg and the hole and, consequently, the risk of damage to the components being disassembled. [ABSTRACT FROM AUTHOR]

The paper examines how cold isostatic pressing (CIP) of powder samples preformed by uniaxial pressing at up to 0.4 GPa influenced the density, coercive force, structure, hardness, and phase composition of the WC–8 wt.% Co (VK8) hardmetal after sintering in vacuum. A multiplication installation was employed for cold isostatic pressing. Transformer oil served as the pressure transmission medium. The density of the CIP samples increased linearly with pressure prior to sintering and reached its maximum at 0.2 GPa for the sintered CIP samples. The coercive force increased nonmonotonically with pressure. The WC grains refined when CIP pressure increased to 0.2 GPa but slightly coarsened after CIP at 0.3 and 0.4 GPa. The Co layer became thinner with pressure being increased to 0.3 GPa and slightly thicker at a pressure of 0.4 GPa. An intermetallic Co0.8W0.2 phase emerged in the samples subjected to preliminary CIP at 0.4 GPa. Hardness measurements at different loads up to 300 N showed that hardness increased at CIP pressures up to 0.3 GPa and slightly decreased in CIP at 0.4 GPa. Scanning electron microscopy photographs of the indenter imprints showed massive cracking of the WC grains. The results were analyzed using experimental data published previously on the effect of high isostatic pressure on the multiplication of dislocations and the fracture of single crystals. Those papers found that the deformation and fracture of single crystals under high isostatic pressures were accompanied by a sharp increase in the dislocation density. Each WC particle was compressed from all sides by the neighboring WC and Co particles, resulting in quasi-isostatic compression. However, the compressive forces are not equal in quasi-isostatic compression conditions, and there is always one force that is greater than the others. This force causes deformation or fracture leading to the mechanical activation of the powder because the imperfection of its particles increases and in turn influences the properties acquired by the hardmetal. [ABSTRACT FROM AUTHOR]

In reservoir simulation, it is important to understand the mechanical behaviour of fractured rocks and the effect of shear and tensile displacements of fractures on their aperture. Tensile opening directly enhances the fracture aperture, whereas shear of a preexisting rough-walled fracture creates aperture changes dependent on the local stress state. Since fracture dilatation increases reservoir permeability, both processes must be included in a realistic and consistent manner into the mechanical reservoir simulation model. Here, we use the extended finite volume method (XFVM) to conduct flow and geomechanics simulations. In XFVM, fractures are embedded in a poroelastic matrix and are modelled with discontinuous basis functions. On each fracture segment the tractions and compressive forces are calculated, and one extra degree of freedom is added for both the shear and tensile displacement. In this particular XFVM implementation we assume that linear elasticity and steady state fluid pressure adequately constrain the effective stress. In this paper, shear dilation is not calculated a posteriori, but it enters the equations such that aperture changes directly affect the stress state. This is accomplished by adding shear dilation to the displacement gradients and therefore ascertains a consistent representation in the stress-strain relations and force balances. We illustrate and discuss the influence of this extra term in two simple test cases and in a realistic layer-restricted two-dimensional fracture network subjected to plausible in situ stress and pore pressure conditions. [ABSTRACT FROM AUTHOR]

In this paper, a novel efficient energy absorber with free inversion of a metal foam-filled circular tube (MFFCT) is designed, and the axial compressive behavior of the MFFCT under free inversion is studied analytically and numerically. The theoretical analysis reveals that the energy is mainly dissipated through the radial bending of the metal circular tube, the circumferential expansion of the metal circular tube, and the metal filled-foam compression. The principle of energy conservation is used to derive the theoretical formula for the minimum compressive force of the MFFCT over free inversion under axial loading. Furthermore, the free inversion deformation characteristics of the MFFCT are analyzed numerically. The theoretical steady values are found to be in good agreement with results of the finite element (FE) analysis. The effects of the average diameter of the metal tube, the wall thickness of the metal tube, and the filled-foam strength on the free inversion deformation of the MFFCT are considered. It is observed that in the steady deformation stage, the load-carrying and energy-absorbing capacities of the MFFCT increase with the increase in the average diameter of the metal tube, the wall thickness of the metal tube, or the filled-foam strength. The specific energy absorption (SEA) of free inversion of the MFFCT is significantly higher than that of the metal tube alone. [ABSTRACT FROM AUTHOR]

This paper presents a literature review of research undertaken on the out-of-plane behaviour of masonry infilled frames. This paper also discusses the effects of bidirectional loads, openings, slenderness, boundary conditions etc. As numerous researchers have reported, these effects play a crucial role in achieving arching action cause, as they can bypass or limit its effectiveness. Namely, arching action leads to additional compressive forces which resist traversal ones. This is confirmed by inertial force methods of testing, while the same cannot be claimed for inter-storey drift or dynamical methods. It is to be acknowledged that most experimental tests were carried out using inertial force methods, mostly with the use of airbags. In contrast, only a few were undertaken with dynamical methods and just two with inter-storey drift methods. It was found that inertial force and inter-storey drift methods differ widely. In particular, inertial force methods damage the infill, leaving the frame more or less intact. Conversely, drift heavily damages the frame, while infill only slightly. Openings were investigated, albeit with contrasting results. Namely, in all cases, it was found that openings do lower the deformational but not all load-bearing capacities. Furthermore, analytical models have shown contrasting results between themselves and with experimental data. Models' stabilities were checked with single- and multi-variable parametric analysis from which governing factors, influences of frame and other parameters were identified. [ABSTRACT FROM AUTHOR]

In the present paper, we propose a method aimed at the mathematical simulation of deformable threadlike (wire) inclusions based on the replacement of their influence on the elastic medium by tensile/compressive forces distributed along their axes. We construct a regularized integral equation of the problem external with respect to the inhomogeneity and develop mathematical models of inhomogeneity that take into account the conditions of contact and enable one to determine the required distribution of forces along the axis of inhomogeneity. An approach to the solution of the posed problems is proposed. For the case of a rectilinear elastic thread-like inclusion of finite length, we obtain an approximate solution of the problem in the closed analytic form. [ABSTRACT FROM AUTHOR]

In this paper, analytical and experimental methods are used to study the deformation mechanisms of metal foam-filled circular tubes in axial splitting and curling modes. Metal foam-filled tubes with prefabricated cracks are placed on a die, and axial compressive experiments are conducted. In the experiments, the force–displacement curves of metal foam-filled tubes are measured, and the deformation modes of metal foam-filled tubes are observed. An analytical model is established for metal foam-filled circular tubes in axial splitting and curling modes. In the analytical model, energy is dissipated by splitting, curling, and plastic bending of the tubes, as well as by friction between the tubes and die and foam compression. The analytical, numerical and experimental results are compared. The analytical model captures the experimental results reasonably well, and the numerical results are in good agreement with experimental ones. It is found that, in the stage of steady deformation, the axial compressive force increases with the increase in the number of prefabricated cracks, the ratio of radius to the wall-thickness and the semi-angle of conical die. The axial compressive force decreases with the increase in the ratio of the prefabricated-crack length to the wall-thickness. Foam-filled tubes have a higher specific energy absorption than sandwich tubes. [ABSTRACT FROM AUTHOR]

Abstract—The results of laboratory experiments on concurrent active acoustic and deformation monitoring of a hydraulic fracture are presented. The experiments were carried out in a model material based on gypsum. For comparison, reference experiments were performed to study the propagation of ultrasonic waves through a liquid-filled gap of controlled width between two precision glass plates. The purpose of the experiments was to study the dependence of the amplitude of the ultrasonic wave passing through the fracture on the value of its opening. In these experiments, a circular hydraulic fracture was created with the plane perpendicular to the axis of the cylindrical sample. A cased injection well was located along the same axis, ending at the middle of its height. The sample was placed between two aluminum alloy disks equipped with piezoceramic transducers built into them, operating in both the emitter and the receiver modes. The working liquid was supplied to the fracture through the channel in the lower disk. The sample was saturated with pore fluid through the upper disk. The entire assembly was placed in a hydraulic press providing a constant compressive force. The fracture opening value varied with the flow rate of the liquid supplied to the center of the fracture and was measured by the relative change in the distance between the disks of the assembly using inductive displacement transducers. Experiments were also carried out simulating a fracture filled with proppant. In this case, the fracture aperture varied as a function of the vertical force applied to the sample. Based on the results of experiments carried out under various conditions, the dependences of the amplitude of the ultrasonic wave that passed through the fracture were plotted. It has been experimentally established that sound attenuation in the hydraulic fracture, which has a natural roughness, is twice lower than in the gap between precision glass plates. The obtained results will make it possible to estimate the value of the hydraulic fracture opening in laboratory experiments conducted on larger samples using active acoustic monitoring. [ABSTRACT FROM AUTHOR]

Behaviour of plant material to mechanical compression depends on the physical properties of plant stalks and their resistance to compressive force. Rind with a high content of lignocellulosic fiber is a potential material for structural strength of the crop that participates in transfer of the loading stresses. The purpose of the study was to calculate mechanical properties of Erianthus arundinaceus cane with rind and without rind. Consequently, force deformation and stress and strain of the cane samples were studied which enumerate the basic essential information to determine the mechanical properties of cane under mechanical compression testing condition. Erianthus arundinaceus is a crop gaining momentum due to its potential for renewable energy value. The various parameters related to mechanical compression was studied using Universal Testing Machine (UTM). It was found that the clone IK76-93 × SF 06-48 yielded the maximum compression load. Maximum displacement force 9.04 kN was required to compress the Erianthus stem with rind, and the minimum displacement force was enabled at 5.13 kN for the clone IK76-81 × GC04-09. The clones without rind exhibited the maximum displacement force at 9.04 kN for the clone IK76-93 × SF 06-48, and the minimum was for the clone IK76-81 × GC04-09 at 3.86 kN. Information on the displacement profile of Erianthus clones gave a better understanding of the stem and rind behavior, and this would be helpful in designing crusher rollers for paper industry. [ABSTRACT FROM AUTHOR]

The buckling and postbuckling of a shear-deformable cantilever is studied using Reissner's geometrically exact relations for the planar deformation of beams. The cantilever is subjected to a compressive follower force whose line of action passes through a spatially fixed point. To study the buckling behavior, a consistent linearization of equilibrium and kinematic relations is introduced. The influence of shear deformation and extensibility on the critical loads is studied. The buckling behavior turns out to crucially depend on the ratio between the shear stiffness and the extensional stiffness of the structure. Closed-form solutions in terms of elliptic integrals for buckled configurations of the cantilever are derived in the present paper. [ABSTRACT FROM AUTHOR]

The cylindrical die forced throughfeed rolling process for gears was proposed to overcome an end-effect behavior of the standard radial-feed gear rolling process which can result in pitch variation and excessive axial end-flow. In the rolling process, the workpieces are pushed through the gap of the rolling tools to form the gear teeth. Understanding of material flow is important for grasping the cause of defect formation and improving the quality of formed gears. In this paper, the material flow behavior of the gear forced throughfeed rolling process was studied on the flow velocity and displacement of key locations by using finite element analysis (FEA). The experiment was also conducted and its blank was sliced to thin pieces, and the grid pattern (GP) was utilized to track the trajectory of flowing materials. The results show that the end-flow is located at the root rather than the tooth crest of the formed workpiece, because the compressive forces from rolling tool mainly take effect at the root of the formed workpiece. The asymmetry of circumferential flow displacements with respect to the gear teeth results in the asymmetrical flanks defect, and this is due to the meshing between teeth of rolling tool and workpiece. The local displacement in the radial direction is larger than that in the circumferential direction. [ABSTRACT FROM AUTHOR]

In this paper, the embedded discontinuity approach is applied in finite element modeling of rock in compression and tension. For this end, a rate-dependent constitutive model based on (strong) embedded displacement discontinuity model is developed to describe the mode I, mode II and mixed mode fracture of rock. The constitutive model describes the bulk material as linear elastic until reaching the elastic limit. Beyond the elastic limit, the rate-dependent exponential softening law governs the evolution of the displacement jump. Rock heterogeneity is incorporated in the present approach by random description of the mineral texture of rock. Moreover, initial microcrack population always present in natural rocks is accounted for as randomly-oriented embedded discontinuities. In the numerical examples, the model properties are extensively studied in uniaxial compression. The effect of loading rate and confining pressure is also tested in the 2D (plane strain) numerical simulations. These simulations demonstrate that the model captures the salient features of rock in confined compression and uniaxial tension. The developed method has the computational efficiency of continuum plasticity models. However, it also has the advantage, over these models, of accounting for the orientation of introduced microcracks. This feature is crucial with respect to the fracture behavior of rock in compression as shown in this paper. [ABSTRACT FROM AUTHOR]

This paper investigates both stability and vibration of nonlocal beams or plates in the presence of compressive forces. Various nonlocal structural models have been proposed to capture the inherent scale effects of lattice-based beams or plates. These nonlocal models are either based on continualization of the difference equations of the original lattice problem (labeled as continualized nonlocal models), or developed from phenomenological nonlocal approaches such as Eringen's type nonlocality. Considered herein are several continualization schemes that lead to either fourth or sixth order spatial governing differential or partial differential equation. Even if the new continualized nonlocal plate models differ in their mathematical description, they appear to furnish very close macroscopic results as shown from asymptotic expansion arguments. The continualized nonlocal beam and plate models and the phenomenological approaches are also introduced from variational arguments. The key role of boundary conditions is shown especially for Eringen's nonlocal model that is not necessarily variationally based. For each of them, the buckling load and the natural frequencies are determined for simply supported beams and plates and compared to their counterparts obtained from the lattice model. The small length scale coefficient of the nonlocal beam or plate models is intrinsically constant and problem independent for the continualized approaches, whereas it is calibrated for the phenomenological models based on the equivalence with the reference microstructured model and consequently, depends on the load, the buckling or vibration mode or the aspect ratio. It is found that the nonlocal continualized approaches are more efficient than the nonlocal phenomenological ones. For beam problems, continualized nonlocal and phenomenological approaches such as Eringen's nonlocal theory can become the same. However, for plate problems, phenomenological approaches may differ significantly from continualized nonlocal ones; thereby offering one the opportunity to have a new class of two-dimensional nonlocal models. [ABSTRACT FROM AUTHOR]

Subject of the present work is the enhancement of the buckling load of beam-type structures under a compressive force by means of active feedback control. The focus of this paper lies on experimental aspects that show the feasibility of the proposed approach. For this purpose, a cantilever beam loaded by a compressive force is considered. The compressive force is applied with the help of a cable which is fixed at the tip of the free end and passes through the foundation of the cantilever. A laser displacement sensor is used to measure the structural displacements at the beam's tip. For actuation, piezoelectric transducers are attached on each side of the cantilever beam. Two kinds of constant gain feedback control approaches are investigated on the experimental setup. The buckling load could be increased by a factor of 2.05. The experimental results agree very well with the performed numerical simulations. As a theoretical basis, a consistent theoretical formulation is presented using the Bernoulli-Euler beam theory. The formulation of the system includes also a general feedback controller with discrete displacement measurements and distributed piezoelectric patches. The influence of the controller on the buckling load, control amount by means of applied voltage and limits of the investigated active buckling control approaches are emphasized. [ABSTRACT FROM AUTHOR]

In this paper, mechanical properties and buckling behavior of single-walled silicon carbide nanocones (SWSiCNCs) are studied using a finite element method. The elastic moduli of SWSiCNCs with different dimensions including different apex angles and lengths are presented. For large apex angles, it is shown that the effect of nanocone length on the elastic modulus can be neglected. Besides, the critical compressive forces of SWSiCNCs are computed. The influences of dimensions and boundary conditions on the buckling behavior of SWSiCNs are studied in detail. The results show that increasing the nanocone apex angle leads to decreasing the critical compressive force. [ABSTRACT FROM AUTHOR]

The curved steel-concrete-steel (SCS) sandwich shell was recently proposed to resist blast loading and it showed better blast resistant performance as compared to flat SCS sandwich shell via developing compressive force along the shell. In this paper, a dimensionless Pressure-Impulse (P-I) diagram was constructed as a convenient tool to predict the damage level of curved SCS sandwich shell subjected to uniformly distributed blast loading. The curved SCS sandwich shell was equivalent to a single-degree-of-freedom (SDOF) system and the equation of motion was established by employing the Lagrange's equation. To construct the dimensionless P-I diagram, the energy balance method was utilized to yield the pressure and impulse asymptotes and the responses in the dynamic response regime were obtained via employing the SDOF method. Then, the finite element method was employed to validate the developed dimensionless P-I diagram. Finally, the procedures of using the constructed dimensionless P-I diagram to quickly conduct the blast resistant design of curved SCS sandwich shell were presented. [ABSTRACT FROM AUTHOR]

Increasing the bending and shear capacities of reinforced concrete members is an interesting issue in structural engineering. In recent years, many studies have been carried out to improve capacities of reinforced concrete members such as using post and pre-tensioning, Fiber Reinforced Polymer and other techniques. This paper proposes a novel and significant technique to increase the flexural capacity of simply supported reinforced concrete beams. The proposed method uses a new reinforcement bar system having bent-up bars, covered with rubber tubes. This technique will avoid interaction of bent-up bars with concrete. They are located in the zone where compressive and tensile forces act against one another. The compressive force in the upper point of the bent-up bars is exerted to the end point of these bars located under neutral axis. Moreover, the tensile stress is decreased in reinforcements located under the neutral axis. This will cause the Reinforced Concrete (RC) beam to endure extra loading before reaching yield stress. These factors may well be considered as reasons to increase bending capacity in the new system. The laboratory work together with finite element method analysis were carried out in this investigation. Furthermore, bending capacity, ductility, strength, and cracking zone were assessed for the new proposed system and compared with the conventional model. Both the FEM simulation and the experimental test results revealed that the proposed system has significant impact in increasing the load bearing capacity and the stiffness of the RC beams. In the present study, an equation is formulated to calculate bending capacity of a new reinforcement bar system beam. [ABSTRACT FROM AUTHOR]

This research focuses on the evolution of mechanical behavior of bimodal mixtures undergoing compaction and diametrical compression. The clusters were built and discrete element method (DEM) was used to investigate the densification process and micromechanics of bimodal mixtures. Additionally, a more comprehensive investigate of the respective breakage of the bimodal mixtures has been carried out. On this basis, qualitative and quantitative analysis of the compressive force, force chain, contact bonds and density field evolution characteristics of the clusters are investigated during the compression process. The entire loading process of the clusters is divided into three stages: rearrangement, breakage and elastic–plastic deformation. Additionally, there are differences in the evolution of micromechanics behavior of different particles in the bimodal mixture, with pregelatinized starch breakage and deformation occurring before microcrystalline cellulose. With the tablet deformation, the fragmentation process of the tablet started at the point of contact and extended toward the center, and the curvature of the force chain increased. This approach may potentially hold a valuable new information relevant to important transformation forms batch manufacturing to advanced manufacturing for the oral solid dosage form. [ABSTRACT FROM AUTHOR]

Highlights: A core-sheath structured coaxial composite fiber with highly aligned and densely stacked boron nitride nanosheets arrangements in the sheath was successfully fabricated. The coaxial fibers have an ultrahigh axial Herman orientation parameter of 0.81, thermal conductivity of 17.2 W m−1 K−1, and tensile strength of 192.5 MPa. The coaxial fibers exhibit intensively potential applications in the wearable thermal management textile. Hexagonal boron nitride nanosheets (BNNSs) exhibit remarkable thermal and dielectric properties. However, their self-assembly and alignment in macroscopic forms remain challenging due to the chemical inertness of boron nitride, thereby limiting their performance in applications such as thermal management. In this study, we present a coaxial wet spinning approach for the fabrication of BNNSs/polymer composite fibers with high nanosheet orientation. The composite fibers were prepared using a superacid-based solvent system and showed a layered structure comprising an aramid core and an aramid/BNNSs sheath. Notably, the coaxial fibers exhibited significantly higher BNNSs alignment compared to uniaxial aramid/BNNSs fibers, primarily due to the additional compressive forces exerted at the core-sheath interface during the hot drawing process. With a BNNSs loading of 60 wt%, the resulting coaxial fibers showed exceptional properties, including an ultrahigh Herman orientation parameter of 0.81, thermal conductivity of 17.2 W m−1 K−1, and tensile strength of 192.5 MPa. These results surpassed those of uniaxial fibers and previously reported BNNSs composite fibers, making them highly suitable for applications such as wearable thermal management textiles. Our findings present a promising strategy for fabricating high-performance composite fibers based on BNNSs. [ABSTRACT FROM AUTHOR]

Mechanical characterization of sub-micron thin films or similar small scale structures have been a continuous challenge to the mechanics community due to the difficulty in accurately quantizing the applied load and the resulted deformation. In this paper, a new force-domain analog-to-digital converter (F-D ADC) created from the concept of Flash ADC in electronics is developed to perform thin film tensile tests. The key component of the F-D ADC is a quantizer-array of microfabricated buckling beams of varying lengths. During testing, the tensile force applied in the test specimen is converted to the compressive force in the quantizer beam array and digitized by using the critical buckling load of the beams as they progressively buckle with increasing force amplitude. The deformation of the specimen is controlled by the piezoelectric actuator. Successful testing of (110) single crystal silicon and titanium/nickel (Ti/Ni) multilayer thin film specimens demonstrated the feasibility of this novel F-D ADC concept. [ABSTRACT FROM AUTHOR]

A new physical head model with air bubble to simulate the brain injury in head decelerating impact is presented in this paper. This new method has its advantage on investigating the brain injury using a direct and visual technique. A hollow transparent glass model was used to simulate the skull, and a transparent gel was used to substitute the brain tissue. Three air bubbles were created in the gel at the respective position of coup site (impacting site), middle site and contrecoup site (opposite to impacting site). After this, the head model was made to free fall from a position and impact on a fixed platform. The decelerating impacting process was recorded by a high-speed video camera and an accelerometer system. Through analysing the video, the volume change, namely, the mean pressure change of the air bubbles were calculated and compared. The results showed explicitly and effectively that during the decelerating impact the contrecoup site air bubble was exposed mainly to a negative pressure which could lead to a tensile stress; and the coup site air bubble was exposed mainly to a positive pressure which could form a compressive force. [ABSTRACT FROM AUTHOR]

Purpose: Performing resistance exercises unilaterally, athletes must activate stabilizing muscles to maintain balance position, and for the same relative load, compressive forces on the spine are reduced providing more safety. Our aim was to compare the effects of resistance training when bilateral and unilateral exercises were used. Methods: Twenty-six young handball players first participated in a 6-week control phase consisting of handball training only, and were later divided into a unilateral and a bilateral group in the experimental phase. Before and after the control and experimental phases, tests of horizontal and vertical jumping, lateral running with change of direction, standing and jump shots with the dominant and nondominant arms were performed. Results: Simultaneous performance of handball and resistance training resulted in greater progress in power and agility compared to handball training alone. The average progress of the unilateral group was greater on all measured variables. However, the differences reached statistical significance only in triple jump and throwing with the non-dominant arm (p < 0.05). Conclusion: Young handball players achieved similar or greater power and agility with unilateral resistance exercises than with bilateral resistance exercises. Considering the benefits unilateral resistance exercises bring, this type of training is highly recommended. [ABSTRACT FROM AUTHOR]

Buckling of uniformly and not uniformly compressed tower buildings, resting on Winkler type soil, is investigated. An equivalent beam is introduced, able to capture the essential behavior of the building. It is a 3D Timoshenko beam, modeled in the framework of a direct approach, whose constitutive law is derived via a homogenization procedure, which includes the effect of the column prestress. The continuous model is discretized via finite differences, and a linear bifurcation analysis is carried out by solving an algebraic eigenvalue problem. Numerical results are shown for sample problems, aimed at detecting the structural behavior, and illustrating the role of some mechanical parameters. Results supplied by the equivalent beam model are compared with those derived by finite element analyses, carried out on three-dimensional frames. [ABSTRACT FROM AUTHOR]

The tensile strength and cracking behavior of layered rocks in a tensile stress field are one of the most significant characteristics of rock masses, which may strongly affect the stability of rock structures. The study presented here investigated the effect of layer spacing and inclination angle on the indirect tensile strength, crack development, failure pattern, and contact force chain of layered disks under diametral loading using experimental and numerical investigations. Numerous experimental models made from plaster were examined under diametral loading, and a two-dimensional Particle Flow Code (PFC2D) was adopted for in depth simulation of the failure process. Both numerical and experimental results were found to be in great agreement and showed that the increase in the layer orientation up to 15° results in the peak in the tensile strength followed by a decrease. Specimens with the spacing ratio (SR) of 0.5 and 0.1 showed the highest and lowest tensile and compressive stresses at the disk center, respectively. Moreover, the numerical analysis indicated the formation of three failure pattern types: TL, PB, and TL-PB. Tensile cracks mainly formed in the direction of diametral loading, and their maximum number formed at 15° and SR = 0.5. Additionally, the shear ones formed in a conjugate system and had negligible numbers. The analysis of the contact force chain showed that the layers do not affect the compressive force chain at α < 45° but at higher angles, the stronger layers transfer compressive force. However, when α ranges from 0° to 30°, tensile forces are distributed in stronger layers, and with an increase in α, the concentration of these forces in these layers diminishes and the forces are reoriented in the direction of diametral loading. [ABSTRACT FROM AUTHOR]

Investigating the extension of aftershocks and the rupture mechanism can effectively constrain the geometric structure of a seismogenic fault and provide a scientific explanation for the earthquake rupture model and the seismogenic structure. On January 8, 2022, an MS6.9 earthquake occurred in Menyuan County, Qinghai Province. The epicenter was located at the intersection of the Tuolaishan and Lenglongling faults in the Qilian-Haiyuan fault zone. The precise relocation of the earthquake sequence shows that the mainshock appeared to be an asymmetric bilateral rupture. The fault plane had a steep dip angle and was inclined toward the SW. The Menyuan earthquake sequence was characterized by two obvious belts with NWW and SSE orientations, exhibiting clear segmentation and non-uniform spatial characteristics. The focal mechanism solutions of the mainshock and partially mediated aftershocks with MS ≥ 4.0 indicate that the source type of the four early aftershocks was consistent with that of the mainshock, predominantly strike-slip faulting, while the two large later aftershocks located at the eastern tip of the aftershock belt were mainly thrust-type. This reveals that the terminus of the mainshock rupture was arrested by the bifurcation fault of the Lenglongling fault. The release of energy from recent accumulated compressional tectonic stress led to the variation in the types of earthquakes. The regional stress inversion indicates that the focal region is undergoing compression in the NE direction, consistent with the northeast convergence of the characteristics of the stress field of the northeast margin of the Qinghai-Tibet Plateau. Integrated with the regional geotectonic environment, we infer that the seismogenic fault of the mainshock was associated with the Tuolaishan fault. The earthquake rupture propagated simultaneously toward the connected Tuolaishan and Lenglongling faults, generating a typical strike-slip cascading rupture event, and the energy release of the mainshock was concentrated at the intersecting fault. The Menyuan earthquake revealed the complexity and heterogeneity of the fracture at the intersection of the faults under a strike-slip regime. In addition, it also revealed that the occurrence of large-scale strike-slip earthquakes in the Qilian-Haiyuan fault zone accommodates the compressive force from the northeastern margin of the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

Additive manufacturing has been used for the production of high-value complex parts. Implementation of structural health monitoring (SHM) methods to these parts would let them gain continuous sensing and damage identification capability. The small size and very strong vibration damping characteristics of additively manufactured polymer parts do not allow the direct use of many SHM methods. In this study, detection and location estimation of compressive force applied to an additively manufactured part made of PLA was examined. The test specimen was designed with multiple skin thicknesses in each of the five zones and completely digital excitation was implemented on the part. Surface Response to the Excitation (SuRE) method was used in this study. Two piezoelectric elements were used for exciting the specimen with lamb waves from one side and recording the dynamic response to excitation at the other end of the part. The digital excitation included multiple pulses with different widths covering a wide range of exciting frequencies. Two different methods were used for damage localization, Deep Learning (DL) and the two-dimensional sum of the squares of differences (2DSSD). Short-time Fourier Transformation (STFT) was used to convert the experimental time-domain sensory data into the time–frequency domain (spectrograms). Two-dimensional images of the spectrograms were classified using 2DSSD and Convolutional Neural Network (CNN). CNN could estimate the compressive force application zone with better than 97% accuracy. [ABSTRACT FROM AUTHOR]

The 3D nonaxisymmetric local stability loss problem is studied for a hollow cylinder, made of a viscoelastic composite material, under the axial compression. The criterion of an infinitesimal initial imperfection is employed, and the evolution of this imperfection is investigated by 3D geometrically nonlinear exact equations of viscoelasticity theory. The corresponding nonlinear problem is solved by the boundary perturbation method. The material of the cylinder is modeled as a viscoelastic transversely isotropic medium. Numerical results for the critical time and critical compressive forces are presented, discussed, and compared with those obtained by approximate shell theories. [ABSTRACT FROM AUTHOR]

We determined energy levels of the hydrogen bridge in nanojunctions with platinum, gold, or copper anchors. The nanojunctions were modeled in the balanced gain and loss energy scheme. It was shown that the sufficiently strong electron flow through the nanojunction can lead to the reduction in the number of allowed energy levels in the bridge. Over a certain value of the energy of flow, the number of electronic states decreases from six to four and the states with the highest energy disappear. This effect is related to the P T symmetry breaking of the electronic Hamiltonian of the bridge. Subsequently, for still higher values of energy characterizing the electron flow, the bridge disintegrates if subjected to the influence of the stretching force ( F < 0 ) exerted by its anchors. On the other hand, if the exerted force is the compressive one ( F > 0 ), the stability of the hydrogen bridge is ensured by its anchors, and its electronic energy structure is still characterized by four closely spaced energy levels. [ABSTRACT FROM AUTHOR]

Tubular lipid membranes (TLMs) are formed by an external pulling force from artificial or biological bilayer vesicles and can be subsequently stabilized by incorporating proteins or amphiphilic polymers into the lipid bilayer. The arising spontaneous curvature of the lipid sheet allows switching off the pulling force without TLM destabilization. However, here we show that during this process two different thermal fluctuation modes drastically increase their amplitudes making fluctuations of the TLM much greater than its radius. Due to the system's proximity to the critical fluctuation point, a weak axial compressive force is sufficient to destabilize the TLM. Its absolute value is shown to be much smaller than that of the pulling force required for the initial lipid nanotube formation. Induced complex instability was studied in the frame of Landau phase transition theory. The process involves two consecutive second-order phase transitions and leads to the tube deformation combining annular corrugation with completely unconventional chiral buckling. Graphical abstract: [ABSTRACT FROM AUTHOR]

In this paper, we will find an explicit optimal lower bound for the first eigenvalue of a fourth order measure differential equation, motivated by physical problems when some physically meaningful measurement is fixed. We establish a variational characterization for the first eigenvalue of the fourth order measure differential equation and find the explicit optimal lower bound for the first eigenvalue. As an application, we will find the explicit optimal lower bound for the first eigenvalue of a vibrating beam which represents the smallest axial compressive force necessary to cause the beam to buckle. [ABSTRACT FROM AUTHOR]

Scattering of obliquely incident surface gravity wave by a semi-infinite floating elastic plate in the presence of lateral compressive force is studied within the framework of blocking dynamics in time-space. In the presence of lateral compressive force, primary and secondary wave blocking occur for two different values of time-period where the group velocity vanishes, whilst the phase velocity remains positive. Moreover, for each time-period within the limits of blocking points, three propagating wave modes exist in the plate-covered region, out of which two are related with positive group velocities and another one is associated with the negative group velocity. Further, all the three wave modes coalesce at the saddle point for a particular value of the compressive force. The energy identity for the scattering problem in the case of multiple propagating modes depends on the amplitude of the reflected and transmitted waves as well as the ratio of the energy transfer rate. In the case of obliquely incident waves, full-wave reflection occurs beyond a critical angle for a certain time-period whilst the same phenomenon occurs for certain incident angles before a critical time-period. Moreover, the scattering coefficients are having removable singularities at the blocking as well as saddle points. Besides, irregular pattern in plate deflection occurs due to the superposition of multiple propagating wave modes for a certain time-period within the blocking limits. The normal strain in the floating plate sheet has a certain oscillatory pattern for the time-period lying within the limits of blocking points. Surface plots for the scattering coefficients as well as plate deflection are demonstrated for various values of incident angle as well as compressive force. A comparison of various results in the case of small amplitude wave theory and shallow water approximation reveals the accuracy of the analysis in different cases. [ABSTRACT FROM AUTHOR]

The composite approach is very effective in developing multiferroic systems with remarkable magnetoelectric coupling coefficients. In this work, P(VDF-HFP)-based films containing 2, 4, 8 and 16 wt% Y3Fe5O12–Na0.5K0.5NbO3 nanocrystalline particles were developed via a simple solvent cast process. In order to facilitate the β-phase crystallization of the P(VDF-HFP), hydrated ferric nitrate was utilized during the preparation of the films, which resulted in significant improvement in the β-phase content. Moreover, the use of Y3Fe5O12–Na0.5K0.5NbO3 also triggered the β-phase crystallization of the P(VDF-HFP). At the highest filler loading of 16 wt%, a magnetoelectric coefficient of 33.6 mV cm−1 Oe−1 was achieved. Piezoelectric energy harvesting studies were also carried out using the composite film containing 16 wt% Y3Fe5O12–Na0.5K0.5NbO3 nanocrystalline particles. A maximum open-circuit voltage of 3.79 V was measured when a compressive force of 5 N was applied to the energy harvesting device. [ABSTRACT FROM AUTHOR]

The Toca das Onças cave is one of the most important Quaternary mammal deposits of Brazil. Two different hypotheses have been proposed to explain the preservation mode of its skeletal remains: either the animals climbed down into the cave, or it could have functioned as a natural trap. Evaluation of pathological modifications on three articulated vertebrae of a single adult giant ground sloth Eremotherium laurillardi reveals a particular type of bone fracture caused by compressive force on the vertebral column, which split the vertebral bodies in the sagittal plane. This diagnosis suggests that the animal accidentally fell into the cave, in accordance with the second hypothesis proposed to the incorporation mode of skeletal remains into the cave. [ABSTRACT FROM AUTHOR]

The impact-sliding wear behavior of steam generator tubes in nuclear power plants is complex owing to the dynamic nature of the mechanical response and self-induced tribological changes. In this study, the effects of impact and sliding velocity on the impact-sliding wear behavior of a 2.25Cr1Mo steel tube are investigated experimentally and numerically. In the experimental study, a wear test rig that can measure changes in the impact and friction forces as well as the compressive displacement over different wear cycles, both in real time, is designed. A semi-analytical model based on the Archard wear law and Hertz contact theory is used to predict wear. The results indicate that the impact dynamic effect by the impact velocity is more significant than that of the sliding velocity, and that both velocities affect the friction force and wear degree. The experimental results for the wear depth evolution agree well with the corresponding simulation predictions. [ABSTRACT FROM AUTHOR]

The buckling delamination problem for a rectangular composite plate with a rectangular inner crack subjected to biaxial compressive forces is considered. It is assumed that the plate considered is simply supported at all its lateral sides, to which uniformly distributed compressive forces are applied. It is also supposed that the surfaces of crack faces have initial infinitesimal imperfections before loading of the plate. The evolution of these imperfections under the action of the biaxial compressive forces is studied within the scope of the threedimensional geometrically nonlinear field equations of the theory of elasticity for anisotropic bodies. For determining the critical buckling delamination force and the buckling delamination mode of the plate considered, an initial imperfection criterion is used. For solution of the corresponding boundary-value problems, the boundary-form perturbation technique and the 3D FEM are employed. Numerical results illustrating the influence of the materials and geometrical parameters of the plate on the critical force are presented and discussed. [ABSTRACT FROM AUTHOR]

Cu 2O flower/grass-like nanoarchitectures (FGLNAs) were fabricated directly on two category specimens of Cu foils and Cu film using thermal oxidation method. The FGLNAs are approximately 3.5 to 12 μm in size, and their petals are approximately 50 to 950 nm in width. The high compressive stress caused by a large oxide volume in the Cu 2O layer on the specimen surface played an important role in the growth of FGLNAs. The effects of surface conditions, such as the surface stresses, grain size, and surface roughness of Cu foil and Cu film specimens, on the FGLNA growth were discussed in detail. PACS: 81. Materials science; 81.07.-b Nanoscale materials and structures: fabrication and characterization; 81.16.Hc Catalytic methods [ABSTRACT FROM AUTHOR]

Three-column osteotomy (3-CO) is a powerful technique in adult deformity surgery, and pedicle subtraction osteotomy (PSO) is the workhorse to correct severe kyphotic spinal deformities. Aging of the population, increasing cases of iatrogenic flat back deformities and understanding the importance of sagittal balance have led to a dramatic increase of this surgical technique. Surgery, however, is demanding and associated with high complication rates so that every step of the procedure requires meticulous technique. Particularly, osteotomy closure is associated with risks like secondary fracture, translation, or iatrogenic stenosis. This step is traditionally performed by compression or a cantilever maneuver with sometimes excessive forces on the screws or instrumentation. Implant loosening or abrupt subluxation resulting in construct failure and/or neurological deficits can result. The aim of this prospective registry study was to assess the efficacy and safety of our surgical PSO technique as well as the osteotomy closure by flexing a hinge-powered OR table. In a series of 84 consecutive lumbosacral 3-CO, a standardized surgical technique with special focus on closure of the osteotomy was prospectively evaluated. The surgical steps with the patients positioned prone on a soft frame are detailed. Osteotomy closure was achieved by remote controlled bending of a standard OR table without compressive or cantilever forces in all 84 cases. This technique carries a number of advantages, particularly the reversibility and the slow speed of closure with minimum force. There was not a single mechanical intraoperative complication such as vertebral body fracture, subluxation, or adjacent implant loosening during osteotomy closure, compared to external cohorts using the cantilever technique (p = 0.130). The feasibility of controlled 3-CO closure by flexing a standard OR table is demonstrated. This technique enables a safe, gentle closure of the osteotomy site with minimal risk of implant failure or accidental neurological injury. [ABSTRACT FROM AUTHOR]

The two-dimensional time-dependent problem of evolution of an initial perturbation in fluid with an ice cover floating on the fluid surface is solved in the linear formulation. In the undisturbed state the longitudinal fluid velocity varies linearly with depth. The ice cover is simulated by a thin elastic plate with taking into account the compressive forces. The integral representation of solution that describes the behavior of the ice cover is constructed. Asymptotics of this solution for large times which make it possible to describe the far fields of perturbations both in the neighborhood and far from the wave front are obtained. [ABSTRACT FROM AUTHOR]

Results of solutions to problems of determining the parameters of anisogrid lattice structures of spacecraft bodies are presented. These problems include analyzing the deformability of a body loaded with transverse inertial forces, determining the fundamental frequency of transverse vibrations of a cantilevered body, studying the deformability of a body loaded with axial compressive force, and analyzing the deformability of a body with an internal fuel tank loaded with transverse inertial forces. The problems under consideration are solved using a continuous model of the lattice structure of a cylindrical body and the finite-element method. [ABSTRACT FROM AUTHOR]

The myocardium is a diverse environment, requiring coordination between a variety of specialised cell types. Biochemical crosstalk between cardiomyocytes (CM) and microvascular endothelial cells (MVEC) is essential to maintain contractility and healthy tissue homeostasis. Yet, as myocytes beat, heterocellular communication occurs also through constantly fluctuating biomechanical stimuli, namely (1) compressive and tensile forces generated directly by the beating myocardium, and (2) pulsatile shear stress caused by intra-microvascular flow. Despite endothelial cells (EC) being highly mechanosensitive, the role of biomechanical stimuli from beating CM as a regulatory mode of myocardial-microvascular crosstalk is relatively unexplored. Given that cardiac biomechanics are dramatically altered during disease, and disruption of myocardial-microvascular communication is a known driver of pathological remodelling, understanding the biomechanical context necessary for healthy myocardial-microvascular interaction is of high importance. The current gap in understanding can largely be attributed to technical limitations associated with reproducing dynamic physiological biomechanics in multicellular in vitro platforms, coupled with limited in vitro viability of primary cardiac tissue. However, differentiation of CM from human pluripotent stem cells (hPSC) has provided an unlimited source of human myocytes suitable for designing in vitro models. This technology is now converging with the diverse field of tissue engineering, which utilises in vitro techniques designed to enhance physiological relevance, such as biomimetic extracellular matrix (ECM) as 3D scaffolds, microfluidic perfusion of vascularised networks, and complex multicellular architectures generated via 3D bioprinting. These strategies are now allowing researchers to design in vitro platforms which emulate the cell composition, architectures, and biomechanics specific to the myocardial-microvascular microenvironment. Inclusion of physiological multicellularity and biomechanics may also induce a more mature phenotype in stem cell–derived CM, further enhancing their value. This review aims to highlight the importance of biomechanical stimuli as determinants of CM-EC crosstalk in cardiac health and disease, and to explore emerging tissue engineering and hPSC technologies which can recapitulate physiological dynamics to enhance the value of in vitro cardiac experimentation. [ABSTRACT FROM AUTHOR]

Green roofs are a key measure used to alleviate the urban heat island effect and reduce stagnant water from urban runoff. However, the expensive substrate material and high construction cost restrict the large-scale application of green roofs. Wheat straw (WS) contains abundant nutrients needed for plant growth; however, burning this straw waste causes severe environmental pollution. In this study, six pretreatment methods, including mixed, soaked, hydrothermal, ultrasonic, microwave, and steam explosion, and three liquid media, including deionized water, acetic acid, and wood vinegar, were used to treat WS to improve its properties and decrease its environmental pollution effects. The results showed that, compared to other treatments, physical methods (microwave, ultrasonic) used in conjunction with wood vinegar could effectively break down the particle structure of WS and increase porosity. Most of the crystallinities were reduced by 1.45–6.66% compared to WS when using these methods, and the absolute values of the surface zeta potential were reduced by 4.224.67 mV. Additionally, the contents of macromolecular lignocellulose, which is difficult to decompose, were reduced by 3.6613.75%. Compared with the use of deionized water or acetic acid, wood vinegar reduced the compressive force of the WS substrates and the energy consumption of compression. Hydrophilic groups such as hydroxyl were introduced into the WS to increase the water absorption rate. Overall, the microwave-assisted wood vinegar pretreatment was an effective method for improving the WS properties for use as a potential alternative substrate material in green roof construction. [ABSTRACT FROM AUTHOR]

Vacuum conveyor belt punching process by using the piercing punch which cooperates with the die has potential to be modified in aspects of lowering the perforation force, extending the tool life, and improving the hole quality in the perforated belts. All these parameters have an influence on the efficiency of the process and strictly depends on the punch geometry. This indicates that based on these criteria the optimization of the tool constructional features may be performed. In the presented research, authors have shown the linear correlation between the resistance force of the compressed material of the multilayer polymer composite belt in punching and the efficiency of the process. It was also proved that using the effective geometry of the piercing punch with spherical bowl can reduce the perforation force by 69%. Based on the obtained model, the simplified optimization as well as the evaluation of the punches with defined geometry can be performed, since all characteristics of the material compressive force obtained for the effective punches were almost consistent. For proper analysis, it is necessary to use the combination of the analytical and numerical modelling, computer simulations with using the finite element method (FEM) and the experimental tests. However, by performing simple compression tests for various tool geometry on the strength testing machine, it is possible to perform the comparison analysis of different piercing punches based on the derived models. This approach can be used to evaluate the properties of selected tools for the groups of materials with wide divergence of the mechanical properties without performing the complex research. [ABSTRACT FROM AUTHOR]

In this study, the buckling behavior of functionalized single- and double-walled boron-nitride nanotubes (SWBNNTs and DWBNNTs) with a monomer of chitosan using molecular dynamics (MD) simulations is explored. The effect of chemical adsorption of chitosan molecule on the critical buckling force and strain is investigated. The results show that the critical buckling force considerably increases as the chitosan is attached to the side wall of boron-nitride nanotube which is more considerable for larger radii of nanotube. Moreover, increasing the number of walls reduces the sensitivity of boron-nitride nanotube to the functionalization compared with similar SWBNNTs. Further, it is shown that critical buckling of functionalized BNNTs increases by rising the weight percentage of chitosan. Considering the critical strain, it is observed that functionalization reduces the critical strain of functionalized BNNTs which is more pronounced in the case of SWBNNTs with bigger radii. Moreover, the buckling mode shape of functionalized BNNTs is presented. [ABSTRACT FROM AUTHOR]

The design and development of self-charging supercapacitor power cells are rapidly gaining interest due to their ability to convert and store energy in an integrated device. Here, we have demonstrated the fabrication of a self-charging supercapacitor using siloxene sheets as electrodes and siloxene-based polymeric piezofiber separator immobilized with an ionogel electrolyte. The self-charging properties of the fabricated device subjected to various levels of compressive forces showed their ability to self-charge up to a maximum of 207 mV. The mechanism of self-charging process in the fabricated device is discussed via "piezoelectrochemical effect" with the aid of piezoelectrochemical spectroscopy measurements. These studies revealed the direct evidence of the piezoelectrochemical phenomenon involved in the energy conversion and storage process in the fabricated device. This study can provide insight towards understanding the energy conversion process in self-charging supercapacitors, which is of significance considering the state of the art of piezoelectric driven self-charging supercapacitors. Devices that are capable of energy harvesting and storage are attractive for meeting daily energy demands, however they are limited by efficiency. Here the authors fabricate a siloxene-based self-charging supercapacitor power cell and probe the piezoelectrochemical effect involved in the charging process. [ABSTRACT FROM AUTHOR]

There have been intensive and continuous research efforts in large-scale controlled assembly of one-dimensional (1D) nanomaterials, since this is the most effective and promising route toward advanced functional systems including integrated nano-circuits and flexible electronic devices. To date, numerous assembly approaches have been reported, showing considerable progresses in developing a variety of 1D nanomaterial assemblies and integrated systems with outstanding performance. However, obstacles and challenges remain ahead. Here, in this review, we summarize most widely studied assembly approaches such as Langmuir-Blodgett technique, substrate release/stretching, substrate rubbing and blown bubble films, depending on three types of external forces: compressive, tensile and shear forces. We highlight the important roles of these mechanical forces in aligning 1D nanomaterials such as semiconducting nanowires and carbon nanotubes, and discuss each approach on their effectiveness in achieving high-degree alignment, distinct characteristics and major limitations. Finally, we point out possible research directions in this field including rational control on the orientation, density and registration, toward scale-up and cost-effective manufacturing, as well as novel assembled systems based on 1D heterojunctions and hybrid structures. [ABSTRACT FROM AUTHOR]

Femoral neck nonunion in young patients has always been a difficult problem to deal with for surgeons. Numerous surgical procedures to address either the biological or mechanical issues at the nonunion have been described and most of them have been associated with variable results. Isolated biological augmentation is often associated with poor results and some techniques like vascularized grafting may require not so commonly available expertise. Valgus osteotomy is aimed to correct the abnormal fracture biomechanics associated with femoral neck fractures. By altering the nature of force transmission across the nonunion, shear forces are converted into compressive forces that lead to rapid osseous union without the need for bone grafting. Though the principles are sound and were described a long time ago, the technical aspects have evolved over time. Various modifications have been described to overcome shortcomings such as limb length discrepancy, reduction of femoral offset, alteration in mechanical axis, and the overall proximal femur anatomy. In this review, we look back at the fundamental principles and recent literature on the results of valgus intertrochanteric osteotomy for femoral neck pseudoarthrosis. We also highlight the important need for accurate preoperative planning and surgical execution. Lastly, we elaborate on the technical improvisations that have happened over time in order to improve functional results and to minimize complications and poor outcome after a valgus osteotomy. [ABSTRACT FROM AUTHOR]

Shear induced particle pressure occurs in concentrated suspensions of particles. Importantly, the significance of the shear induced particle pressure has not been recognized in polymer rheology. The shear induced particle pressure results in an inward pressure on the polymer chains resulting in a shear dependent compressive force. The analytical form of the force balance equations that incorporate the effect of shear induced particle pressure predict a reduced polymer blob size and reducing viscosity with increasing shear rate as has been observed experimentally. Power law behavior is found for the viscosity in accord with the general observations for concentrated polymer rheology. [ABSTRACT FROM AUTHOR]

Energy efficient buildings are unimaginable without highly insulating thermal envelopes. Mineral wool among others is a popular material for thermal insulation. Architects and engineers usually use the data given by the manufacturer in the specification of the material for their building physical design. Such data are obtained from laboratory measurements, carried out on non-aged, and dry samples. However, moisture could affect the thermal performance of insulation materials and may affect the durability too. In the research, we examined stone mineral wool hardboard thermal insulations, which were obtained from a flat roof. The samples looked differently: some of them were in good condition and maintained their load bearing capability, but some were spoiled and soft. We measured and compared the used samples' thermal conductivity, sorption isotherm and deformation under compressive force to new etalon samples. We also investigated the reason behind the lack of load bearing durability of the built-in and spoiled mineral wool boards using scanning electron microscopy and derivatography. In our study, we show how built-in conditions changed the thermal and mechanical properties and thermal performance of the mineral wool insulation layer, which could degrade by up to 40% in terms of thermal resistance under built-in conditions due to certain spoiling and production mistakes of mineral wool. [ABSTRACT FROM AUTHOR]