Uniform Force Research Articles

Highly reproducible van der Waals integration of two-dimensional electronics on the wafer scale.

Two-dimensional (2D) semiconductors such as molybdenum disulfide (MoS2) have attracted tremendous interest for transistor applications. However, the fabrication of 2D transistors using traditional lithography or deposition processes often causes undesired damage and contamination to the atomically thin lattices, partially degrading the device performance and leading to large variation between devices. Here we demonstrate a highly reproducible van der Waals integration process for wafer-scale fabrication of high-performance transistors and logic circuits from monolayer MoS2 grown by chemical vapour deposition. By designing a quartz/polydimethylsiloxane semirigid stamp and adapting a standard photolithography mask-aligner for the van der Waals integration process, our strategy ensures a uniform mechanical force and a bubble-free wrinkle-free interface during the pickup/release process, which is crucial for robust van der Waals integration over a large area. Our scalable van der Waals integration process allows damage-free integration of high-quality contacts on monolayer MoS2 at the wafer scale and enables high-performance 2D transistors. The van-der-Waals-contacted devices display an atomically clean interface with much smaller threshold variation, higher on-current, smaller off-current, larger on/off ratio and smaller subthreshold swing than those fabricated with conventional lithography. The approach is further used to create various logic gates and circuits, including inverters with a voltage gain of up to 585, and logic OR gates, NAND gates, AND gates and half-adder circuits. This scalable van der Waals integration method may be useful for reliable integration of 2D semiconductors with mature industry technology, facilitating the technological transition of 2D semiconductor electronics.

Bending-bending coupled static analysis of functionally graded and porous pretwisted cantilever beams using initial values method

In this study, the bending-bending coupled static behavior of functionally graded and porous pretwisted cantilever Timoshenko beams is reported. Symmetric power-law distribution is employed as the material profile and it is assumed that porosity can disperse over the cross-section in two forms namely, even and uneven distributions. Two different yet equivalent forms of governing equations are obtained by formulating the problem in the fixed and curvilinear coordinate systems, respectively. The initial values method is adopted as the solution methodology. While the fundamental matrix is computed numerically by using the multiplicative integral of Volterra to obtain the solution in the fixed coordinate formulation, the matrix exponential which allows for obtaining exact expressions is utilized in the curvilinear coordinate formulation. Exact analytical deflection expressions are presented for space-fixed vertical tip force and body-fixed uniform distributed force cases. It is shown that both formulation approaches yield consistent results with each other and those obtained from the finite element analyses. In addition, several parametric studies that investigate the effects of the volume fraction index, porosity coefficient, and porosity distribution on the tip deflections are presented.

Splice Connections for Built-Up Column Assemblies in Cold-Formed Steel Construction

The development of simple connection methods is necessary for increasing cold-formed steel (CFS) construction activities. A new splice connection concept for the CFS built-up column-to-column connections is presented in this paper. This simple connection concept will use the same size and shape of the geometry as the CFS built-up column, which will enable a quick erection process. The new splice connection configurations, arrangement, and installation methods for cold-formed steel construction are demonstrated. Twenty-eight experiments, which include four actual columns, two disconnected columns, and 22 columns with splice connections, are carried out. This paper examines the influence of various parameters of splice connections such as length, thickness, and number of fastener rows. The design strength of the actual column is determined using the direct strength method (with modified global and local slenderness approaches) and is compared with the results of the splice connected columns for adequacy. The force transfer mechanism and failure modes of splice connection components are demonstrated in the form of detailed sketches. The smaller length splice connections led to localized failures, while the longer splice connections enabled the uniform force distribution between the built-up column cross-sections. Finally, it is recommended that the splice connection configuration should be a minimum of 300 mm in length, the splice thickness should be equal to the CFS built-up cross-section, and two rows of fasteners for attaining the required design strength of the built-up column members.

Precise Shrink Fitting Design of the High Strength Gear Mold for the Precision Forging of Noncircular Spur Bevel Gears

Shrink fitting of forging mold (SFFM) is an effective method for improving mold strength, extending the mold's service life and reducing the manufacturing cost of forging mold. However, due to the asymmetric geometry and complex stress distribution, the precise design of SFFM for the precision forging of noncircular bevel gears is very difficult. In this paper, a new precise design method of SFFM for the precision forging of noncircular bevel gears is proposed, which mainly includes the following five parts. First, a new design method for the mold parting surface-the curved surface parting method-is proposed to design the forging mold of noncircular spur bevel gears. Then, new dimension design methods for the gear mold and shrink rings based on the uniform shrinkage force are proposed. Third, a new design method for the inhomogeneous interference value between shrink rings and the gear mold is developed to provide a precise, uniform shrinkage force. After that, a strength correction method for the shrink-fitted gear mold is proposed to ensure the gear mold and shrink rings have sufficient strength both in the assembly process of the shrink-fitted gear mold and precision in the forging process of noncircular spur bevel gears. Ultimately, finite element simulations and verification experiments are performed to verify the proposed precise design method of SFFM for the precision forging of noncircular bevel gears. The precise design method of SFFM proposed in this paper is not only applicable to the precise design of the high-strength gear mold for noncircular bevel gears, but can also provide a valid reference for the precise design of the high-strength mold for other complicated asymmetric parts.

Revisiting the Mechanisms of ENSO Response to Tropical Volcanic Eruptions

AbstractStratospheric volcanic aerosol can have major impacts on global climate. Despite a consensus among studies on an El Niño‐like response in the first or second post‐eruption year, the mechanisms that trigger a change in the state of El Niño‐Southern Oscillation (ENSO) following volcanic eruptions are still debated. Here, we shed light on the processes that govern the ENSO response to tropical volcanic eruptions through a series of sensitivity experiments with an Earth System Model where a uniform stratospheric volcanic aerosol loading is imposed over different parts of the tropics. Three tropical mechanisms are tested: the “ocean dynamical thermostat” (ODT); the cooling of the Maritime Continent; and the cooling of tropical northern Africa (NAFR). We find that the NAFR mechanism plays the largest role, while the ODT mechanism is absent in our simulations as La Niña‐like rather than El‐Niño‐like conditions develop following a uniform radiative forcing over the equatorial Pacific.

Automated process planning in milling of hybrid components

Hybrid material composites can meet the increasing demands for high strength and low weight due to their different workpiece properties. Usually, hybrid components require post-machining after their fabrication. Due to the different material properties, new challenges arise in the machining process. It is essential to recognize the course of the material boundary in order to adapt the process planning accordingly and to enable a uniform material transition during machining. This paper presents a method for automated material recognition and automatic adaptation of the process parameters considering a uniform force level during the milling of hybrid materials. This way, the load on the milling tool in the material transition area can be reduced by up to 71%, which prevents premature tool failure. An optical laser line scanner is used to localize of material transitions within hybrid components. This enables a digital mapping of the material distribution in the discretized workpiece model. In combination with an empirical force model, it is possible to predict the cutting forces of the different materials and determine the material transition area for adapting them to specified target values.

Trapping of a Single Microparticle Using AC Dielectrophoresis Forces in a Microfluidic Chip.

Precise trap and manipulation of individual cells is a prerequisite for single-cell analysis, which has a wide range of applications in biology, chemistry, medicine, and materials. Herein, a microfluidic trapping system with a 3D electrode based on AC dielectrophoresis (DEP) technology is proposed, which can achieve the precise trapping and release of specific microparticles. The 3D electrode consists of four rectangular stereoscopic electrodes with an acute angle near the trapping chamber. It is made of Ag-PDMS material, and is the same height as the channel, which ensures the uniform DEP force will be received in the whole channel space, ensuring a better trapping effect can be achieved. The numerical simulation was conducted in terms of electrode height, angle, and channel width. Based on the simulation results, an optimal chip structure was obtained. Then, the polystyrene particles with different diameters were used as the samples to verify the effectiveness of the designed trapping system. The findings of this research will contribute to the application of cell trapping and manipulation, as well as single-cell analysis.

Effect of strand molecular length on mechanochemical transduction in elastomers probed with uniform force sensors

The impact of strand molecular length on mechanical response is elucidated through the incorporation of uniform mechanochromic force probes.

Design and cyclic testing of a gusset plate connection for precast concrete buckling-restrained braced frames

A design method for precast concrete buckling-restrained braced frames with traditional gusset plate connections has not yet been codified. In addition, experimental data for this novel system are lacking. The primary objectives of this research were to design and experimentally test a partial system under representative seismic loads and to determine the applicability of the uniform force method (UFM) for connection interface force distribution. A quasi-static cyclic test was performed on a scaled, partial system. Experimental results showed that the UFM alone does not accurately predict interface forces for this system because the method does not account for frame action. Results also showed that there is some change in column base fixity as the frame undergoes larger horizontal displacements. This was the first U.S. laboratory test on a scaled, partial version of this system. Development of a codified design method would require further testing to determine an appropriate interface force distribution and quantify the change in column base fixity.

Consistency of Imperfections in Steel Eurocodes

The second-order theory was used to analyze the flexural buckling of an individual member simply supported on both member ends, with a uniform double symmetric cross-section under a uniform axial force in an elastic state. The purpose was to show the influence of four different amplitudes of initial imperfections on the shape of the elastic buckling mode ηcrx used in the current EN 1993-1-1 and its new draft, prEN 1993-1-1. Three methods were followed for the analysis: the equivalent member (EM) method, the unique global and local initial (UGLI) imperfection method, and second-order theory with the initial imperfection having an initial local bow imperfection e0. For the relevant quantities, simple formulae were derived and their distribution was drawn on diagrams to represent their graphical interpretations for the first time ever. The formulae and diagrams were valid for the ultimate limit state, which means NEd=Nb,Rd. The influence of four different amplitude values was evaluated: (a) e0,k, proposed for the UGLI imperfection method in the draft EN 1993-1-1; (b) the initial local bow imperfection e0, utilized in the current EN 1993-1-1; (c) the other one employed in its draft; and (d) e0,d, used in the UGLI imperfection method in the current EN 1993-1-1, the current EN 1999-1-1, and the draft prEN 1999-1-1. The main conclusion was that e0,k must not be used in the draft EN 1993-1-1. The UGLI imperfection method was also applied to the column fixed at one end and simply supported at the other end. This example showed the geometrical interpretation of relevant amplitudes. The historical development of the UGLI imperfection method is also presented. All the relations are illustrated in two numerical examples, and the geometrical interpretations of formulae were used in the diagrams. The partial results were verified by the independent computer programs FE-STAB and IQ 100.

Flexural design of restraining panels in buckling-restrained steel plate shear walls considering high-order buckling modes

Buckling-restrained steel plate shear wall (BRSPSW) is one kind of excellent energy dissipating member. The inner steel plate in BRSPSW usually works with high-order buckling modes to resist lateral force under the buckling restrained effect of outer restraining panels. However, current design of the restraining panels is commonly based on simplified uniform-loaded plates without considering the effect of the high-order buckling modes, which may result in unsafe designs. In this paper, the high-order buckling modes in BRSPSW and their influence on the flexural design of the restraining panels were studied. Finite element (FE) models that can accurately simulate the out-of-plane interaction behavior of BRSPSW were developed and verified by existing test results. The numerical results show that the high-order buckling of the steel plate leads to a series of inclined strip-shaped stress regions on restraining panels. When the parameters of BRSPSW are varied in common range, the positive and negative bending moments of the restraining panel under the strip-shaped force are 9.6 and 2.8 times those under the uniform force, respectively. The differences between the bending moment of the restraining panels under strip-shaped force and that under uniform force become larger as the spacings of the strip-shaped stress regions increase. Furthermore, the spacings of the strip-shaped stress regions increase with the decrease of the height-to-thickness ratio of the steel plate and the increase of the gap between the steel plate and the restraining panel. Two fitting formulas of the positive and negative moment amplification factors considering the effect of the high-order buckling modes are proposed to design the restraining panels safely. Additionally, a simplified model and bending moment equations of the restraining panels in BRSPSW are suggested. To avoid the excessive negative bending moments occurring at side supports of the restraining panel, the ratio of cantilever length to middle span is suggested to be not more than 0.4.

Relative Roles of Land and Ocean Cooling in Triggering an El Niño Following Tropical Volcanic Eruptions

AbstractPaleoclimate evidence suggests that tropical volcanic eruptions could increase the likelihood of El Niño occurrence. Previous numerical model studies with zonally uniform volcanic aerosol forcing suggested the roles of land cooling‐induced monsoon suppression and ocean cooling‐induced air‐sea interaction in triggering an El Niño following the eruption. Here, we perform targeted sensitivity experiments by confining aerosol forcing over land or ocean only in the fully coupled Community Earth System Model to assess relative roles of these land and ocean cooling. Our results indicate that volcanic aerosol over land, especially over the large landmass of tropical Africa, is more effective in exciting an El Niño than over ocean. The suppressed African monsoon excites Kelvin‐wave westerly wind anomalies over the tropical central Pacific, triggering an El Niño through the Bjerknes feedback. Under the uniform ocean aerosol forcing, the Indian Ocean's fast dipole response induces a slow western Pacific El Niño‐like cooling in the second year.

Modeling the timing and extent of glaciations over southeastern Tibet during the last glacial stage

Deciphering the variations of past glaciations over southeastern Tibet which holds the largest mass of contemporary temperate glaciers over Asia helps to advance our understanding of the ice-climate interactions and how glaciers may respond to future climate change. Using an ice sheet model forced by the reconstructed climatic change during the past 88 ka, we investigate the timing and extent of glaciations over southeastern Tibet and explore the potential influences of model parameters and horizontal resolution. Our results illustrate a long-term decreasing trend in the glacierized area during the past 88 ka, suggesting progressively restricted glaciations over southeastern Tibet. Apart from the long-term trend, there are multiple glacier advance events on millennial timescales. The maximum extent of glaciation occurs at late MIS 4 (∼58 ka) and early MIS 3 (∼51 ka), with the minimum glacier extent predicted in the late Holocene (∼4 ka). The evolution of glaciations during the past 88 ka is dominated by the change in air temperature in our simulations in which temperature and precipitation serve as the climatic forcing. Regarding modeling uncertainty, we show that the pattern of glacier evolution is independent of the values of model parameters and horizontal resolution used, but the amplitude of glacier extent is significantly affected, especially for model parameters. Compared with glacial geological evidence, the timing of the modeled widespread glaciations broadly matches with the ages of known moraines, but the mapped glacier bounds across specific mountain ranges are generally underestimated. The adoption of a spatially uniform climatic forcing and the related uncertainty may contribute to the model-data discrepancy. Our results aid in the establishment of a testable link between climate change and glacier response during the last glacial stage and have important implications for glacier behavior in the future.

Emergent isotropy of a wave-turbulent cascade in the Gross-Pitaevskii model

The restoration of symmetries is one of the most fascinating properties of turbulence. We report a study of the emergence of isotropy in the Gross-Pitaevskii model with anisotropic forcing. Inspired by recent experiments, we study the dynamics of a Bose-Einstein condensate in a cylindrical box driven along the symmetry axis of the trap by a spatially uniform force. We introduce a measure of anisotropy A(k, t) defined on the momentum distributions , and study the evolution of A(k, t) and as turbulence proceeds. As the system reaches a steady state, the anisotropy, large at low momenta because of the large-scale forcing, is greatly reduced at high momenta. While exhibits a self-similar cascade front propagation, A(k, t) decreases without such self-similar dynamics. Finally, our numerical calculations show that the isotropy of the steady state is robust with respect to the amplitude of the drive.

Bio-magnetic pulsatile flow of Ti-alloy-Au/blood couple stress hybrid nanofluid in a rotating channel

This research investigates the mobility of blood-carrying titanium (Ti)-alloy-gold (Au) hybrid nanoparticles in a rotating channel when heat radiation, viscous dissipation, and Lorentz force are significant. The couple stress hybrid nanofluid flow between two flat walls saturated with a porous medium. The pulsatile flow is subjected to an inverse magnetic field of uniform force to study the effect of the Lorenz force. The flow has been mathematically modeled, resulting in a delicate partial differential equations (PDEs) system. In addition, the response surface methodology (RSM) is executed to probe the sensitivity of effective flow field parameters on the heat transfer rate. We initially converted the PDEs into ordinary differential equations (ODEs) using the perturbation technique. Numerical solutions of velocity, temperature, heat transfer rate and entropy generation are taken from bvp4c to evaluate coupled ODEs. The results show that the velocity and temperature of the hybrid nanofluid are less for compared with . The heat transfer rate diminishes with large values of the Eckert number and radiation parameter at the left wall. The heat transfer rate has a negative sensitivity on the left wall for all levels of and

Large-eddy simulation of a wind-turbine array subjected to active yaw control

Abstract. This study validates large-eddy simulation (LES) for predicting the flow through a wind turbine array subjected to active yaw control. The wind turbine array consists of three miniature wind turbines operated in both non-yawed and yawed configurations under full-wake and partial-wake conditions, for which wind tunnel flow measurements are available. The turbine-induced forces are parametrised by three different models: the standard actuator disk model (ADM-std), the blade element actuator disk model (ADM-BE), also referred to as the rotational actuator disk model (ADM-R), and the actuator line model (ALM). The time-averaged turbine power outputs and the profiles of the wake flow statistics (normalised streamwise mean velocity and streamwise turbulence intensity) obtained from the simulations using the ADM-std, the ADM-BE and the ALM are compared with experimental results. We find that simulations using the ADM-BE and ALM yield flow statistics that are in good agreement with the wind-tunnel measurements for all the studied configurations. In contrast, the results from LES with the ADM-std show discrepancies with the measurements obtained under yawed and/or partial-wake conditions. These errors are due to the fact that the ADM-std assumes a uniform thrust force, thus failing to capture the inherently inhomogeneous distribution of the turbine-induced forces under partial wake conditions. In terms of power prediction, we find that LES using the ADM-BE yields better power predictions than the ADM-std and the ALM in the cases considered in this study. As a result, we conclude that LES using the ADM-BE provides a good balance of accuracy and computational cost for simulations of the flow through wind farms subjected to AYC.

On the Diffusivity of Moist Static Energy and Implications for the Polar Amplification Response to Climate Warming

Abstract Energy balance models (EBMs) have been widely used in a range of climate problems, but the assumption of constant diffusivity in the parameterization of the moist static energy (MSE) flux can hardly be justified. We demonstrate in this study that the diffusive MSE flux can be derived from the basic energy balance equation with a few tolerable assumptions. The estimated diffusivity is both spatially and seasonally dependent, and its midlatitude average is then tested against several scaling theories for the midlatitude eddy diffusivity. The result supports the diffusivity theory of Held and Larichev modified for the moist atmosphere, affording a dynamics-based parameterization of MSE diffusivity. The implementation of the parameterization in an EBM leads to an interactive MSE diffusivity that accounts for the midlatitude eddy response to climate forcing perturbations. Under a uniform radiative forcing, the EBM with a diffusivity so parameterized produces a weakening of the midlatitude diffusivity and a modestly polar-amplified surface temperature response as an inevitable outcome under the dual constraints of the nonlinear Clausius–Clapeyron relation and the temperature gradient-dependent diffusivity, even in the absence of any poleward-amplifying radiative feedbacks. As the consequence of more isothermal temperature and reduced diffusivity, the variance of the midlatitude surface temperature also decreases with warming.

Microscopic plugging adjustment mechanism in a novel heterogeneous combined flooding system

In this study, novel pre-crosslinked gel particles were synthesized to form a new heterogeneous composite system with a weak alkaline-surfactant-polymer (ASP) system. The microscopic visualization model is used for oil flooding and macroscopic core flooding experiments and advanced testing methods to describe the microscopic morphology of the pre-cross-linked gel particles and their retention state in the porous medium, revealing the microscopic plugging mechanism of the novel heterogeneous composite system in the porous medium. Scanning electron microscope images showed a uniform force on the pre-crosslinked gel particle network structure during the stressing process, with no mechanical weak points and improved tensile properties. The maximum pressure induced by the pre-cross-linked gel particles passing through the 0.5 mm diameter pore plate was 4.8 times higher than that of the conventional bulk particles. The elasticity factor of the pre-cross-linked gel particles was eight times higher than that of the conventional body expansion particles. Adding pre-cross-linked gel particles to the composite system improves the interfacial tension stability and effectively reduces the amount of chemicals under the same interfacial tension level. In a three-tube parallel core flooding experiment, the final heterogeneous composite flooding recovery after polymer flooding was 7.3% higher than that of ASP. The heterogeneous composite flooding system improves the recovery of crude oil after polymer flooding by blocking pore flow steering, wetting reversal, co-emulsification, and poly merging oil zone mechanisms. Thus, the implementation of heterogeneous composite flooding after polymer flooding can achieve the synergistic effect of blocking the dominant seepage channel and improving the oil washing efficiency, which can significantly improve the degree of remaining oil utilization. To clarify the microscopic blocking mechanism of the heterogeneous composite system, it is important to guide the development of post-polymer flooding composite flooding technology and research its microscopic flooding mechanism.

Entropy generation on biomagnetic gold-copper/blood hybrid nanofluid flow driven by electrokinetic force in a horizontal irregular channel with bioconvection phenomenon

Present research deals with the study of time-dependent pulsatile MHD (Magnetohydrodynamics) hybrid nanofluid with entropy optimization and electrokinetic force in a channel. The current mathematical model is formulated as the [Formula: see text] blood (Casson fluid) hybrid nanofluids flow between the bottom and wavy top walls. The pulsatile flow is subjected to an inverse magnetic field of uniform force to study the effect of the resulting Lorenz force. Exact solutions for velocity, temperature, heat transfer rate, and streamlines are constructed by employing the perturbation approach to evaluate coupled nonlinear partial differential equations (PDEs). The velocity [Formula: see text] of the blood-based [Formula: see text] hybrid nanofluid increases with increasing values of the electro-osmotic parameter. The higher values of copper-gold nanoparticle volume fraction increase the entropy generation [Formula: see text]. This theoretical investigation helps estimate entropy in systems biology, which is used to treat cancer and improve the function of medical devices.

Multi-Scale Electrochemo-Mechanical Experiments on Thin Film Battery Materials

The application of a solid-electrolyte may enable the use of certain high energy density anodes like Li and Si and also circumvents the flammable liquid-electrolyte. However, all solid components introduce multiple solid-solid interfaces whose responses are strongly affected by the mechanical state of the region on both sides, which can be affected by a combination of applied stack pressure and cycling induced volumetric change1. Electrochemo-mechanical coupling (ECM) studies2 are a relatively new area for this society, especially with thin film structures,3 which provide high purity, uniformity, and controlled geometries for the reaction to take place. However, correctly interpreting ECM experimental results as well as explaining the fundamental failure mechanisms (i.e. cracking and dendrite propagation) requires careful experimental study of material mechanical properties and how electrochemical characteristics change with mechanical state4.In this work, we describe two experimental studies on sputter-deposited thin-film LixV2O5 electrodes, with a thickness of 1 µm on a Si wafer. A lateral cell design that has the two electrodes on a single plane on a substrate, is described to focus on a single electrode. An ionic liquid electrolyte (ILE) on the Si substrate is used instead of a solid electrolyte pellet to avoid high ohmic losses , and to focus on the mechanics of the LixV2O5. The ILE covers the two electrodes and serves as the ionic pathway. Lithium foil (or vapor-deposited Li metal) is placed on the wafer and serves as the Li source. The first study is conducted with a liquid electrolyte and compares the cell behaviors between stressed and unstressed states. An external mechanical load is applied to the whole electrode surface for a uniform force distribution. An important thermodynamic contribution of stress is the change in equilibrium potential, which can be measured as a function of applied stress on the electrode and may also affect charge transfer kinetics at the interface. The second experiment will focus on the composition modulated mechanical properties of LixV2O5 which is crucial for ECM modeling work. Here, we lithiate V2O5 electrodes to different amounts, remove the electrolyte to stop ionic transport, and then perform nanoindentation in an inert argon environment. The correlation between elastic moduli and x in LixV2O5 as well as the variation of equilibrium potential provide important parameters for building accurate ECM numerical models. Pasta, M., Armstrong, D., Brown, Z.L., Bu, J., Castell, M.R., Chen, P., Cocks, A., Corr, S.A., Cussen, E.J., Darnbrough, E., et al. (2020). 2020 roadmap on solid-state batteries. JPhys Energy 2, 032008.Wan, T.H., and Ciucci, F. (2020). Electro-chemo-mechanical modeling of solid-state batteries. Electrochim. Acta 331, 135355.Spencer Jolly, D., Ning, Z., Darnbrough, J.E., Kasemchainan, J., Hartley, G.O., Adamson, P., Armstrong, D.E.J., Marrow, J., and Bruce, P.G. (2020). Sodium/Na β″ Alumina Interface: Effect of Pressure on Voids. ACS Appl. Mater. Interfaces 12, 678–685.Cao, D., Sun, X., Li, Q., Natan, A., Xiang, P., and Zhu, H. (2020). Lithium Dendrite in All-Solid-State Batteries: Growth Mechanisms, Suppression Strategies, and Characterizations. Matter 3, 57–94.