Dissipation Potential Research Articles

Research on Optimization Design of Prefabricated ECC/RC Composite Coupled Shear Walls Based on Seismic Energy Dissipation

This study explores an advanced prefabricated composite structure, namely ECC/RC composite shear walls with enhanced seismic performance. This performance enhancement is attributed to the strategic use of engineered cementitious composites (ECC) known for their superior ductility. The study conducts both experimental and numerical simulation analyses to scrutinize the seismic energy absorption capabilities of this innovative structure. Emphasis is placed on critical aspects, such as the optimal deployment areas for ECC within composite coupling beams and shear walls, the grade of ECC strength, the proportion of stirrups in coupling beams, and the caliber of longitudinal reinforcement. Through finite element analysis, this research quantitatively assesses the impact of these variables on seismic energy dissipation, incorporating evaluations of load–displacement hysteretic behaviors and the energy dissipation potential of ECC/RC shear wall samples. The findings suggest the optimal ECC application in the coupling beams, and within a 14% structural height at the base of shear walls. Recommended design parameters include an ECC strength grade of E40 (40 MPa), longitudinal reinforcement of HRB400 (400 MPa), and a stirrup ratio in coupling beams of 0.5%.

On the determination of the quasi-static evolution of brittle plane cracks via stationarity principle

The crack front evolution in brittle solids is commonly modelled by defining some crack increment criterion, which can be derived from considerations on the stress singularity, from the definition of a dissipative potential, from the introduction of phenomenological concepts such as the crack mobility, and so on. In this work, we faced the problem with no allowance for any crack increment criterion, but using only the elastic properties, the fracture energy, and a stationarity principle. We will show that these ingredients are enough for determining the equilibrium and the quasi-static evolution of generally shaped three-dimensional brittle plane cracks. In doing this, we pointed out some new insight on the crack front motion, a set of new, generalised, domain integrals for measuring the pointwise crack ‘tension’, and a rigorous calculation of the intersection angle between the crack front and the free surface.

Building a stable and robust anti-interference DNA dissipation system by eliminating the accumulation of systemic specified errors

BackgroundThe emergence of DNA nanotechnology has enabled the systematic design of diverse bionic dissipative behaviors under the precise control of nucleic acid nanodevices. Nevertheless, when compared to the dissipation observed in robust living systems, it is highly desirable to enhance the anti-interference for artificial DNA dissipation to withstand perturbations and facilitate repairs within the complex biological environments. ResultsIn this study, we introduce strategically designed “trash cans” to facilitate kinetic control over interferences, transforming the stochastic binding of individual components within a homogeneous solution into a competitive binding process. This approach effectively eliminates incorrect binding and the accumulation of systemic interferences while ensuring a consistent pattern of energy fluctuation from response to silence. Remarkably, even in the presence of numerous interferences differing by only one base, we successfully achieve complete system reset through multiple cycles, effectively restoring the energy level to a minimum. SignificanceThe system was able to operate stably without any adverse effect under conditions of irregular interference, high-abundance interference, and even multiplex interferences including DNA and RNA crosstalk. This work not only provides an effective paradigm for constructing robust DNA dissipation systems but also greatly broadens the potential of DNA dissipation for applications in high-precision molecular recognition and complex biological reaction networks.

Integrated coplanar waveguide coil on diamond for enhanced homogeneous broadband NV magnetometry.

Nitrogen-vacancy (NV) centers in diamond have emerged as promising quantum sensors due to their highly coherent and optically addressable spin states with potential applications in high-sensitivity magnetometry. Homogeneously addressing large ensembles of NV centers offers clear benefit in terms of sensing precision as well as in fundamental studies of collective effects. Such experiments require a spatially uniform, intense, and broadband microwave field that can be difficult to generate. Previous approaches, such as copper wires, loop coils, and planar structures, have shown limitations in field homogeneity, bandwidth, and integration in compact devices. In this paper, we present a coplanar waveguide (CPW) gold coil patterned on a 3 × 3 mm 2 diamond substrate, offering full integration, enhanced stability, and broad bandwidth suitable for various NV sensing applications. Coil fabricated on diamond offers several advantages for magnetometry with NV centers ensemble, including enhanced heat dissipation, seamless integration, scalability, and miniaturization potential. We optimize critical geometrical parameters to achieve a homogeneous magnetic field with a coefficient of variation of less than 6% over an area of 0.5 mm 2 and present experimental results confirming the performance of the proposed CPW coil.

Preliminary experimental tests of a novel friction damper for seismic retrofit of RC precast structures

Precast RC structures have been widely adopted for industrial and commercial buildings since the ’60 s in the most developed countries. For this structural typology, connections between structural elements set a crucial point in the presence of lateral loads, such as earthquakes, since the deficiency, or lacking, of connection elements is the main responsible for their structural collapse. This paper shows the preliminary mechanical testing of an innovative damping device conceived to be installed in beam-to-column joints of precast RC structures, with a bidirectional dissipative potential due to its geometry. This new Bidirectional Rotation Friction Damper (BRFD) has been designed and optimised after a tribological campaign, which led to the selection of the two different friction interfaces investigated in this work. The mechanical tests have been performed considering the guidelines of EN15129 and the previous tribological investigation findings, showing the influence of sliding frequency and bolt torque increment on the steadiness of the BRFD hysteresis cycle.

A numerical model for chemo-thermo-mechanical coupling at large strains with an application to thermoresponsive hydrogels

The aim of this work is the derivation and examination of a material model, accounting for large elastic deformations, coupled with species diffusion and thermal effects. This chemo-thermo-mechanical material model shows three key aspects regarding its numerical formulation. Firstly, a multiplicative split of the deformation gradient into a mechanical, a swelling and a thermal part. Secondly, temperature-scaled gradients for a numerical design comprising symmetric tangents and, thirdly, dissipation potentials for the modelling of dissipative effects. Additionally, the derived general material model is specialised to thermoresponsive hydrogels to study its predictive capabilities for a relevant example material class. An appropriate finite element formulation is established and its implementation discussed. Numerical examples are investigated, including phase transition and stability phenomena, to verify the ability of the derived chemo-thermo-mechanical material model to predict relevant physical effects properly. We compare our results to established models in the literature and discuss emerging deviations.

Method for the Determination of Rational Constructional and Technological Parameters for the Processes of Powder Materials Forming

The main theoretical aspects of porous and powder materials technological processing is worked out. The proposed material model is based on: - the four-parameter plasticity theory, which reflect the influence of porosity, resistance and the presence of dilatancy of solid phase deformation regime; - the dissipative potential and the load surface expression, that allow to take account such materials elastic - viscous - plastic properties; - the solid phase energy deformation speed with its subsequent over the representative element volume averaging. The peculiarity of this model is that the equilibrium flow concept elastic-viscous-plastic material is an alternative to its elastic-plastic deformation. The proposed equations are suitable for their effective practical using for digital models creation that based on existent software for the of equilibrium processes of compact materials deformation finite–element analysis. The practical use of the proposed methodologies made it possible to determine: - the regularities of the different modules material layers interaction during stamping of bimetallic blanks with an conical working surface; - the porosity distribution over the product volume at the final stage of radial extrusion of the bushings with an internal flange; - the effect of powder material decompression during reverse extrusion of cylindrical products.

Pool boiling heat transfer performance of micro-embossing molds for the fabrication of polymer wicks

As flexible heat dissipation devices are urgently needed for flexible electronics, polymers with the advantages of good flexibility, insulation, and low density have attracted wide attention. It would be interesting to fabricate thermal functional structures on polymers to overcome their low thermal conductivity. This study aims to design and fabricate a micro-embossing mold to process polymer three-dimensional microgroove wicks (3D-MWs), which are applied in flexible heat pipes and achieve high thermal conductivity. Three kinds of tungsten steel molds were processed by using two wire electrical discharge machining processes (WEDM), two electrical discharge shaping machining processes (EDSM), and a combination of WEDM and EDSM. The 3D-MWs of the tungsten steel mold were reprinted onto the polymer films by a two-step embossing process. To investigate the effects of microstructures on boiling heat transfer performances, tungsten steel molds fabricated by different methods were tested to reflect the heat dissipation potential of the polymer 3D-MWs. The results showed that the 3D-MWs fabricated by the combination of WEDM and EDSM exhibit good boiling heat transfer performance and high processing efficiency, with a critical heat flux of 1040.1 kW/m2 and a maximum heat transfer coefficient of 38.4 kW/m2·°C. These values are 46% and 611% higher than those of the smooth tungsten steel surface, respectively, making it a superior choice for micro-embossing molds.

Grain boundary network plasticity: Reduced-order modeling of deformation-driven shear-coupled microstructure evolution

Microstructural evolution in structural materials is known to occur in response to mechanical loading and can often accommodate substantial plastic deformation through the coupled motion of grain boundaries (GBs). This can produce desirable behavior, such as increased ductility, or undesirable behavior such as mechanically-induced coarsening. In this work a novel, multiscale model is developed for capturing the combined effect of plasticity mediated by multiple GBs simultaneously. This model is referred to as “grain boundary network plasticity”. The mathematical framework of graph theory is used to describe the microstructure connectedness, and the evolution of microstructure is represented as volume flow along the graph. By using the principle of minimum dissipation potential, which has previously been applied to grain boundary migration, a set of evolution equations are developed that transfer volume and eigendeformation along the graph edges in a physically consistent way. It is shown that higher-order geometric effects, such as the pinning effect of triple points, may be accounted for through the incorporation of a geometric hardening that causes geometry-induced GB stagnation. The result is a computationally efficient reduced order model that can be used to simulate the initial motion of grain boundaries in a polycrystal with parameters informed by atomistic simulations. The effectiveness of the model is demonstrated through comparison to multiple bicrystal atomistic simulations, as well as a select number of GB engineered and non-GB engineered data obtained from the literature. The effect of the network of shear-coupling grain boundaries is demonstrated through mechanical response tests and by examining the yield surfaces.

Benefits of Open Quantum Systems for Quantum Machine Learning

AbstractQuantum machine learning (QML) is a discipline that holds the promise of revolutionizing data processing and problem‐solving. However, dissipation and noise arising from the coupling with the environment are commonly perceived as major obstacles to its practical exploitation, as they impact the coherence and performance of the utilized quantum devices. Significant efforts have been dedicated to mitigating and controlling their negative effects on these devices. This perspective takes a different approach, aiming to harness the potential of noise and dissipation instead of combating them. Surprisingly, it is shown that these seemingly detrimental factors can provide substantial advantages in the operation of QML algorithms under certain circumstances. Exploring and understanding the implications of adapting QML algorithms to open quantum systems opens up pathways for devising strategies that effectively leverage noise and dissipation. The recent works analyzed in this perspective represent only initial steps toward uncovering other potential hidden benefits that dissipation and noise may offer. As exploration in this field continues, significant discoveries are anticipated that could reshape the future of quantum computing.

Non-equilibrium steady states as saddle points and EDP-convergence for slow-fast gradient systems

The theory of slow-fast gradient systems leads in a natural way to non-equilibrium steady states, because on the slow time scale the fast subsystem stays in steady states that are controlled by the interaction with the slow system. Using the theory of convergence of gradient systems depending on a small parameter ɛ (here the ratio between the slow and the fast time scale) in the sense of the energy-dissipation principle shows that there is a natural characterization of these non-equilibrium steady states as saddle points of a so-called B-function where the slow variables are fixed. We give applications to slow-fast reaction-diffusion systems based on the so-called cosh-type gradient structure for reactions. It is shown that two binary reactions give rise to a ternary reaction with a state-dependent reaction coefficient. Moreover, we show that a reaction-diffusion equation with a thin membrane-like layer convergences to a transmission condition, where the formerly quadratic dissipation potential for diffusion convergences to a cosh-type dissipation potential for the transmission in the membrane limit.

Part-through cracks computation in an Euler–Bernoulli beam model

AbstractThe reduction of the equations of a slender, brittle continuum to a one-dimensional theory and the possibility of accounting for the cracking of this body has received much attention recently. This contribution investigates the effect of cross-sectional geometry on damage localization in an Euler–Bernoulli beam. Two geometric fields characterizing the crack penetration depth on each side of the beam are introduced, from which the modulation of the bending and tensile parts of the strain energy by the crack depth is deduced. The geometry of the crack-tip envelope is obtained by energy minimization. We find that in the case of a Griffith-like dissipation potential, the characteristic size of the crack is a key element for predicting initiation at a finite external load. We can accurately predict the initiation position by regularizing the model in the spirit of Variational Brittle Fracture. Model predictions are compared against computational results obtained by the classical damage field theory.

A variational approach to effective models for inelastic systems

Given a set of inelastic material models, a microstructure, a macroscopic structural geometry, and a set of boundary conditions, one can in principle always solve the governing equations to determine the system’s mechanical response. However, for large systems this procedure can quickly become computationally overwhelming, especially in three-dimensions when the microstructure is locally complex. In such settings multi-scale modeling offers a route to a more efficient model by holding out the promise of a framework with fewer degrees of freedom, which at the same time faithfully represents, up to a certain scale, the behavior of the system. In this paper, we present a methodology that produces such models for inelastic systems upon the basis of a variational scheme. The essence of the scheme is the construction of a variational statement for the free energy as well as the dissipation potential for a coarse scale model in terms of the free energy and dissipation functions of the fine scale model. From the coarse scale energy and dissipation we can then generate coarse scale material models that are computationally far more efficient than either directly solving the fine scale model or by resorting to FE2 type modeling. Moreover, the coarse scale model preserves the essential mathematical structure of the fine scale model. An essential feature for such schemes is the proper definition of the coarse scale inelastic variables. By way of concrete examples, we illustrate the needed steps to generate successful models via application to problems in classical plasticity, included are comparisons to direct numerical simulations of the microstructure to illustrate the accuracy of the proposed methodology.

Experimental study on the thermal performance of a liquid-cooled heat sink integrating heat pipes for dual CPU servers

The increasing power consumption of server CPUs poses a challenge for data center cooling. In this work, a liquid-cooled heat pipe heat sink (LHPHS) with compactly arranged heat pipes is designed and fabricated for CPU cooling in dual CPU servers. Water is selected as the working fluid in the heat pipes. Experiments are conducted to explore the heat dissipation potential of LHPHS under high inlet coolant temperature and high heat load conditions, and to investigate the operational stability of LHPHS under the conditions of uneven heat generation between two CPUs. Furthermore, a one-dimensional thermal resistance network and numerical model of the LHPHS are established to quantitatively analyze the thermal resistance distribution of LHPHS and the variation of thermal resistance with coolant flow rate. The results show that, firstly, the LHPHS operates stably under high inlet coolant temperature and high heat load conditions, meeting the heat dissipation requirements of up to 37.5 W/cm2 with a coolant flow rate of 1 L/min and inlet coolant temperature of 35℃. Secondly, the LHPHS exhibits excellent performance in controlling temperature difference between CPUs and even when there is discrepant heat generation between them. Thirdly, the LHPHS performs a low thermal resistance, measuring 0.044 ℃/W at a coolant flow rate of 0.5 L/min, and this resistance further decreases as the flow rate increases. Additionally, it is observed that the thermal resistance of the liquid-cooled plate decreases with the increasing flow rate, and heat transfer within the heat pipes becomes a critical aspect under high coolant flow rates. Therefore, reducing the thermal resistance of the heat pipe is crucial for the thermal performance improvement of the LHPHS.

A new life cycle impact assessment methodology for assessing the impact of abiotic resource use on future resource accessibility

PurposeAbiotic resource is included as an impact category in life cycle impact assessment (LCIA). The most widely accepted LCIA method is abiotic resource depletion potential (ADP). However, numerous studies have illustrated the limitations of the ADP method, such as the neglect of resources that can be recycled. This paper aims to develop a comprehensive and objective method for assessing the impact of resource use on future generations, which can be used at different stages of the life cycle.MethodsBased on the above research objectives, this paper proposes a new method, the abiotic resource expected dissipation potential (AEDP) method, for assessing the impacts of current resource use on the abiotic resource accessibility. The method is divided into four impact categories based on different endpoints of the dissipative flow and replaces the resource extraction rate with the global annual dissipation rate and adds anthropogenic stocks to the total reserves, resulting in the characterization factor AEDPs. Finally, the four impact categories are weighted to obtain a final impact score for resource use.ResultsResults of the new method are presented as a multi-dimensional reflection of natural reserves, dissipation rates, and extraction rates of resources. The comparison between AEDPs and ADPs revealed differences between them, but they were not significant. A higher power of the total reserves in the AEDP formula can overemphasize the effect of natural reserves on the characterization factor. Furthermore, other natural reserve data was used as alternative indicators in the sensitivity analysis.ConclusionThe new assessment method enables the future impacts of abiotic resource use to be more accurately assessed. It can be used at any life cycle stage to support relevant stakeholder decision-making. However, a broader database is required to be developed to calculate more characterization factors. Moreover, the over-dominance of reserve data in the characterization factors overshadows the influence of other dimensions. Consequently, further research is necessary to improve the operability and plausibility of this method.

Assessment of cooling performance of mini/micro-channel stacked double layer heat sink

A study is accomplished here to investigate the performance of a novel double-layer mini/micro-channel stacked heat sink (DL-MMCHSHS). The hydraulic diameter and aspect ratio of mini-channel heat sink are 0.12 cm and 3, respectively. The width of the fins between two channels is 0.04 cm. The total width of two runners is the same, and its width is 1.44 cm. The heat dissipation potential of this new type of heat sink is investigated. It was observed that the pressure loss is reduced by using the DL-MMCHSHS instead of a single-layer micro-channel heat sink (SL-MCHHS). The reduction in the pressure loss reduces the pumping power, which leads to decrease in operating costs of the system. For the total flow rate of 345.69 cm3/min, the pressure loss reduces about 35.41% by using the DL-MMCHSHS instead of a SL-MCHHS. The uniformity index in the range of 0.077 to 0.192 is achieved in this study. For the total flow rate of 346.64 cm3/min, the uniformity index enhances about 60% with boosting the flow rate ratio from 0.5 to 3.5. For the total flow rate of 1039.26 cm3/min, the thermal resistance increases about 76.22% as the flow rate ratio increases from 0.5 to 3.5.

A standard thermodynamic-based extension of the Modified Cam-Clay soil model and its applications

For mechanical behaviours of granular soils considered here (sands, silts and stiff clays), we propose a thermodynamic-based formulation which relies on the Modified Cam-Clay constitutive model. To this end, and in the framework of Generalized Standard Materials (GSM) framework, we introduce a free energy and a yield criterion (or equivalently a dissipation potential) which account for an isotropic nonlinear elastic behaviour and a volumetric hardening law. Based on available works with coupled hardening laws for von Mises plasticity, we propose for pressure-sensitive materials a new nonlinear deviatoric hardening preserving the well-known critical state existence.Taking advantage of the GSM framework, we establish an incremental variational formulation of the model whose solution obeys to a minimization principle. This has required an approximation of the incremental dissipation. The resulting equations are detailed for the use of an implicit resolution scheme with a standard Newton–Raphson algorithm. The constitutive model parameters are calibrated on a pool of experimental data on isotropic, shearing and triaxial tests on loose sand specimen. The investigations of the model responses allow to better predict the nonlinear regimes of soils specimen on monotonic and cyclic loading paths. Numerical finite element simulations finally underline the predictive capabilities of the model on structures.

Experimental validation of a novel curved steel damper for steel frames with flexible beam-column joints

In this study, results of an experimental program are presented to validate the performance of a novel energy dissipation device (EDD) designed for use in moment-resisting steel frame structures with flexible beam-column connections. The EDD, composed of a curved steel plate, stiffeners, and flanges on both ends, was tested in laboratory conditions using a displacement control quasi-static loading protocol. Three half-scale steel frames were used, one serving as a control and the other two incorporating the device in both column-beam joints. The device was fabricated using two different materials, mild steel, and stainless steel, and the results were compared. The results of the experimental program revealed that the frames equipped with the energy dissipation device performed significantly better than the control frame. This was observed qualitatively, in terms of the amount of damage sustained by the frames, and quantitatively, through measurements of the frames' capacity and displacement ductility. Frames that were equipped with dampers showed an approximately 1.5-fold increase in displacement ductility and an 84–113% increase in cumulative energy dissipation compared to the control frame. Overall, this research highlights the potential of this novel energy dissipation device to enhance the seismic performance of moment-resistance steel frame structures.

Economic value dissipation potential (EVDP): an improved method to estimate the potential economic value loss due to resource dissipation in life cycle assessment

Economic value dissipation potential (EVDP): an improved method to estimate the potential economic value loss due to resource dissipation in life cycle assessment

Energy Dissipation Potentials of Grouped Spur Dikes in an Open Channel

Energy Dissipation Potentials of Grouped Spur Dikes in an Open Channel