Flow Properties Research Articles

Heat and mass transfer analysis of non‐miscible couple stress and micropolar fluids flow through a porous saturated channel

AbstractThis study examines the flow rate, Bejan number transportation, concentration distribution and thermal characteristics of an immiscible couple stress‐ micropolar fluids within a porous channel. The authors focus on the effects of heat radiation and an angled magnetic field on the thermal dispersion, concentration distribution and entropy formation of two different types of incompressible immiscible micropolar and couple stress fluids inside a porous channel. Here, the static walls of the channel are isothermal, and the pressure gradient in the flow domain's entrance zone is constant. In this flow problem, we tried to simulate thermal radiation in the energy equation by applying Rosseland's diffusion approximation. To solve the problem, the authors have used no‐slip conditions at the channel's immovable walls, a continuity of temperature profile, shear stresses, thermal flux, linear velocity, and micro‐rotational velocity over the fluid‐fluid interface. The equations that govern the flow of immiscible fluids are solved using a well‐defined methodology and both the temperature and flow field are then evaluated using a closed‐form solution. The mathematical results of the thermal distribution and flow velocity are used to derive the Bejan number distribution and the entropy generation number. Graphical discussions are used to illustrate the impact of different emerging factors on the model's flow and thermal properties, which describe the major impact of the proposed model. These variables involve the micropolarity parameter, Reynolds number, inclination angle parameter, radiation parameter, and Hartmann number. The outcomes of the present models are corroborated by previously established results available in the literature.

Modeling fast flows with variable water content: A depth-integrated SPH approach

Water content is one important factor on which velocities, heights, and runout of debris flows and similar phenomena depend. To this purpose, we need two ingredients (i) a mathematical model describing the incorporation of water into the moving soil, which results in a change of water content, and (ii) a rheological model with properties depending on the water content. Modeling of such problems can be done either by using either a: (i) two phases approach, where velocities of solid and water may be different, using two sets of nodes, or (ii) two phases approach where velocities of both are assumed to be the same, using a single set of nodes. In both cases, the models have to implement a mechanism for the water inflow -or outflow-. We will modify both types of two phases models (one or two sets of nodes for solid and water) to include the change of water content due to water inflow. Implementation in the SPH requires extending the algorithm and updating the smoothing length because it is based on the mass of particles and their relative position. Updating the smoothing length when only changes mass is to be avoided. Regarding the rheological model, we will introduce a new model for frictional debris flows implementing a Voellmy coefficient which depends on water content. Alternatively, we will propose a more consistent model based on Bagnold’s idea of introducing a 1D concentration parameter (λ). Finally, we will illustrate the proposed model capability with two examples, a dam break problem, and a real case in El Salvador where the water content played an important role in the propagation properties of a debris flow.

Studying the effect of various types of chemical reactions on hydrodynamic properties of dispersion and peristaltic flow of couple-stress fluid: Comprehensive examination

A mathematical model has been constructed to examine the creeping sinusoidal flowing and diffusion of a solute material of an incompressible couple-stress fluid across a porous medium with wall features in the existence of heterogeneous-homogeneous chemical reaction. The mean effective diffusion factor is calculated using the long wavelength hypothesis, Taylor’s limit criteria, and dynamic periphery restrictions. The graphs have been used to study the effects of important constraints on the mean effective diffusion coefficient. The mean effective diffusion factor is found to rise with wall characteristics and amplitude ratio, indicating that peristalsis causes an increase in scattering. Additionally, scattering increased with the permeability constraint but decreased with the couple-stress constraint, homogeneous reaction rates, and heterogeneous reaction rates.

Simulating blood accumulation with improved smoothed particle hydrodynamics in surgical simulation system.

Blood accumulation often occurs during bleeding in surgery. Simulating the blood accumulation in surgical simulation system not only enhances the realism and immersion of surgical training, but also helps researchers better understand the physical properties of blood flow. To realistically simulate the blood accumulation during the bleeding, this paper proposes a novel kernel function with non-negative second derivatives to improve the SPH method. Meanwhile, a simple form of boundary force equation is constructed to impose the solid boundary condition. We simulate the blood accumulation during liver bleeding and vessel bleeding respectively in the surgical simulation system. The simulation results show that there is no occurrence of blood physically penetrating the boundary. Applying the solid boundary condition to the blood by using the method proposed in this paper is not only convenient but can also eliminate compression instability in the blood accumulation simulation.

Paleosol-induced early dolomitization with U[sbnd]Pb age constraints and its implications for fluid pathways in ancient sandstone aquifers

In hydrogeology, a key challenge involves identifying patterns within ancient formations to forecast the distribution of fluid pathways and barriers to permeability, as well as comprehending the palaeohydrological system and its changes over time. This study addresses two main research inquiries concerning fluid flow: firstly, the influence of dolomitization induced by paleosols on flow characteristics, and secondly, the implications for fluid flow pattern distribution in continental sedimentary units. The objectives are pursued through: (1) meticulous, high-resolution measurements of porosity and permeability coupled with well-log data from an outcrop and two boreholes; (2) investigation of petrographic features of diagenetic minerals and their ages using the UPb geochronology system; and (3) an integration of these methodologies to grasp rock properties and fluid flow at a broader scale. Findings suggest that early dolomitization in continental sequences significantly affects fluid flow properties across the basin. The development of paleosols triggered early dolomitization, supported by UPb geochronology evidence. Subsequent groundwater migration along hydraulic gradients, influenced by fluctuations in the local aquifer's water table, facilitated the vertical distribution of dolomitization. Dolomitization occurred in residual pores resulting from initial mineral alteration, early lithifying the sediment and preventing mechanical compaction, thus preserving porosity. During migration events, fluids moved vertically along local faults and horizontally through the dolomitized layers of the formation, which likely remained porous at the time, leading to substantial silica mineralization.

An efficient hybrid WENO scheme with minimized dispersion and adaptive dissipation properties for compressible flows

A numerical scheme with good spectral properties is important for the simulation of compressible flows with various of length scales for fine flow scales resolving. The MDAD-HY scheme (Li et al., 2022) using a discontinuity detector and scale sensor achieves the minimized dispersion and adaptive dissipation property. However, the discontinuity detector is devised based on the ratio of the 1st-order and 2nd-order derivatives on two sides of the interface introducing excessive numerical cost. To address this issue, an efficient hybrid WENO scheme with minimized dispersion and adaptive dissipation properties is proposed in this work. Based on the characteristic-decomposition approach, the numerical flux of the present hybrid scheme is achieved by switching between the linear MDAD scheme and the MDAD-WENO scheme according to a new efficient non-dimensional discontinuity detector. The linear flux is reconstructed in a component-wise method to decrease the characteristic-projection operations. To further improve the spectral property of the present scheme, an adaptive parameter controlling the contribution of the optimal linear scheme according to the discontinuity indicator is introduced. Several benchmark test cases involving broadband of length scales and discontinuities are adopted to verify the efficiency and the high-resolution capability of the present scheme.

Evaluated the effects of nature α-olefins (limonene, β-caryophyllene and camphene) as additives on the cold flow properties of diesel fuel

Pour Point Depressants (PPDs) are currently deemed the most efficacious methodology to enhance the low-temperature fluidity of diesel fuel. However, the majority of these PPDs present complications such as high costs, intricate synthesis procedures, and exhibit potential biotoxicity. To address these challenges, natural α-olefins (β-caryophyllene, limonene and camphene) with 1-hexadecene in varying ratios (5, 10, 15, 20, 25:1) were successfully polymerized at ordinary temperature as poly-α-olefine pour point depressant (PAO PPD), and designated as 1-hexadecane-β-caryophyllene (C16-SZX), 1-hexadecane-limonene (C16-NMX), 1-hexadecane-camphene (C16-KX). An in-depth examination was conducted on the cold filter plugging point (CFPP) and solid point (SP) of both untreated and PPD-added diesel. Subsequently, the finding clearly demonstrates that the CFPP and SP were separately reduced 10 and 32 °C in diesel treated with a molar ratio of 10:1 of C16-KX at the dosage of 2000 ppm. Meanwhile, a comprehensive study was undertaken to investigate the influence of natural α-olefins on the reduction of low-temperature fluidity in diesel fuel. The inhibitory impacts of natural molecular formations on wax crystals were meticulously scrutinized, particularly their roles in modifying the growth patterns of these crystals. Eventually, a novel mechanism by which poly-α-olefine alters the crystalline behavior of wax crystals is proposed.

Pea protein isolate-kappa-carrageenan complex coacervate as a lecithin substitute and their effect on physical properties, polymorphism, and melting behaviour of dark chocolates

This study used pea protein isolate (4% w/w) and kappa-carrageenan (4% w/w) to prepare complex coacervate through electrostatic interactions by optimizing the pH and ratio of protein-to-polysaccharide. The maximum coacervate yield of 81% was achieved at the optimized pH of 3.0 and the protein-to-polysaccharide ratio of 4:1. The optimized coacervate at various concentrations (1, 1.5, 2, 2.5, and 3% w/v) was assessed to emulsify cocoa butter to water fractions. The 2% w/v of complex coacervate successfully emulsified up to 40% aqueous phase in cocoa butter to water fractions whereas complex coacervates at 1%, 1.5%, 2.5%, and 3% w/v were found to stabilize only 20% aqueous phase. The storage and temperature stability of emulsions were higher upon usage of 2% w/v complex coacervate as the serum layer separation was minimal. Based on the emulsion stability observations, complex coacervate (2% w/v) was used to partially and completely substitute lecithin in dark chocolates. The results showed that irrespective of the emulsifiers utilized, the polymorphism and melting behaviour of all chocolates remained the same and retained the desired polymorphic form V. The moisture content and particle size distribution of chocolates did not exceed the acceptable limit. The Casson plastic viscosity (ηca), Casson yield stress (τ0c), and hardness (N) of chocolates significantly (p < 0.05) increased upon increasing the complex coacervate. The present findings revealed that partial substitution (50%) of lecithin with complex coacervate is highly promising for the production of dark chocolates while retaining the desirable flow properties and polymorphism.

A novel porous liquid for enhanced CO2 uptake to improve conversion efficiency

AbstractPorous liquids (PLs) with unique porous frameworks and good flow properties can achieve coupling enhancement for CO2 capture and conversion. In this paper, a series of novel PLs were designed and synthesized using UiO‐66 as the framework and novel bi‐cationic ionic liquids (ILs) as an excluded solvent. The prepared PLs showed significant improvement in CO2 uptake capacity over ILs at different pressures and exhibited excellent CO2 catalytic conversion performance, exceeding the sum of the effects of ILs and UiO‐66. Especially at low pressure, the PLs still showed excellent catalytic performance, but the catalytic performance of the corresponding ILs was significantly reduced, which was due to the rapid adsorption and conversion of CO2 by the porous framework of UiO‐66 to improve the CO2 uptake and transfer efficiency within the ILs, thus achieving coupling enhancement. It can provide a new way to realize the efficient conversion of CO2 under milder conditions.

Mechanical and Physicochemical Characteristics of a Novel Premixed Calcium Silicate Sealer.

The aim of the present in vitro study was to evaluate specific mechanical and physicochemical properties of three calcium silicate-based sealers, BioRoot™ Flow (BRF), CeraSeal (CRS) and TotalFill® (TF). Samples were prepared to evaluate different physicochemical and mechanical properties of the tested sealers. These evaluations were accomplished by investigating the pH changes over time, porosity, roughness, flow properties, compressive strength and wettability. The results were statistically evaluated using one-way analysis of variance. All three sealers demonstrated an alkaline pH from 1 h of immersion in water to 168 h. A higher porosity and hydrophily were detected in BRF samples compared to CRS and TF. No significant difference was found between the tested materials in the flow properties. Lower compressive strength values were observed for BRF compared to TF and CRS. Differently shaped structures were detected on the three materials after 7 days of immersion in PBS. The three materials demonstrated a higher solubility than 3% after 24 h of immersion in water (CRS < BRF < TF). The novel premixed calcium silicate sealer (BRF) had comparable physicochemical properties to the existing sealers. The lower compressive strength values could facilitate the removal of these materials during retreatment procedures. Further studies should investigate the biological effects of the novel sealer.

A Bayesian Approach To Locally Varying Regularization In Optical Flow Velocimetry

A recent method for determining accurate, dense velocity fields from a pair of particle images is to solve the optical flow problem, but the ill-posed inverse problem of optical flow velocimetry (OFV) generally entails minimizing a weighted sum of two terms--fidelity and regularization--and the weights in the sum are parameters that require manual tuning based on the flow properties and particle images. This tuning of the weighting parameters makes the experimental applicability of the method much more challenging as the calculated velocity field has demonstrated sensitivity to the value of the weights. This work proposes a hierarchical model for the weighting parameters in the framework of maximum a posteriori (MAP)-based Bayesian optimization approaches. The resulting method is tested on three different synthetic datasets and on experimental particle images. The method is found to be capable of self-adjusting the local weights of the optimization process in real-time while simultaneously determining the velocity field, leading to a more accurate estimate of the velocity field without requiring any dataset-specific manual tuning of parameters.

Microfluidic flow sensor based on chronoamperometric measurements in a microchannel

Microfluidics explores the fluid behavior at micron scale and is therefore suited to applications that need precise manipulation of fluids at small length or volume scales. In a span of over two decades, microfluidics has become an essential tool for modern genome sequencing platforms, single-cell analysis and common diagnostic tests. Despite many successful applications, the field has various challenges: Fabrication processes are yet to transition to commercial materials, microfluidic systems are reliant on skilled operators, and supporting equipment. Technological innovations in automation are needed to enable easy to use, completely on-chip microfluidic systems. Sensors are a critical component of any automated system. Fluid and flow properties such as flow rate, pressure, temperature, viscosity are critical to applications in drug development, and material/chemical synthesis. The flow rate (μL/min or nL/min) predictions based on external (off-chip) flow measurements can lead to erroneous calculations. The present work explores a technique based on chronoamperometry to measure flow rates inside a microchannel. Chronoamperometry based redox cycling of aqueous NaCl was performed by using interdigitated electrodes (IDE). The sensor measures current transients (which are modulated by the flow rate of the solution) effected by redox reactions on surface of the electrodes. The sensor demonstrated a sensitivity of 0.016 (μL/min)−1 change in charge transfer per unit change in flow rate and 3σ resolution of 9.3 μL/min. The calibration curve is linear in the range 0 – 200 μL/min, with a limit of detection (LoD) of 5 μL/min, making it suitable for various microfluidics applications.

Simultaneously enhancing the flow properties and mechanical strength of polyphenylene sulfide via in‐mold ultrasonic‐assisted injection molding

AbstractInjection molding is widely used for making intricate plastic products due to its precision, cost efficiency, and fast production. Industries like consumer electronics, aerospace, and medical, demand high mechanical properties from these parts. However, high‐performance polymers face challenges in flowability. Ultrasonic‐assisted injection molding offers a solution, but its impact on flowability and mechanical properties is not fully understood. We propose a novel injection mold design with in‐mold ultrasonic vibration to address this. By applying high‐frequency shear forces to the melt, it alters polymer chain alignment, enhancing flow and microstructure. Employing polyphenylene sulfide (PPS) resin as the primary material, this study systematically explores the impact of varying ultrasonic vibration durations and stages on melt filling behavior and product performance. Compared with conventional molds, ultrasonic‐assisted molds reduce melt viscosity by 38% and improve mechanical properties by 10.21%, with a 17.1% increase in crystallinity. This technology shows promise for improving flowability and mechanical properties in injection molding, with potential for wide industrial application.

Ionic strength effect on the structure and dynamics of colloidal dispersions with weak attractive interactions

We present a macro- and microrheological study of the effect of ionic strength on the phase behavior, structure and flow properties of colloidal dispersions stabilized by short-range repulsive interactions inferred via co-polymerization of weak acid groups. We investigated the impact of ionic strength, by varying the concentration of natrium chloride (NaCl), on dispersions with only repulsive interactions, but also when additional attractive depletion forces are present due to added non-absorbent polymer, namely polyethyleneoxide (PEO). For dispersions with only repulsive electrosteric interactions, at low particle volume fractions (ϕ < 0.4), increasing ionic strength hardly affects the relative viscosity whereas at higher particle volume fractions, a decrease in viscosity is observed due to a reduced range of electrosteric repulsion between particles, corresponding to a reduction of the effective particle volume fraction ϕeff. For dispersions including attractive interactions, at volume fractions ϕ = 0.45 below the hard sphere freezing point (ϕc=0.5), independently of the ionic strength, the bulk viscosity increases monotonically with increasing PEO concentration due to the transition from a fluid to a fluid/crystalline and finally to a gel state. However, the increase in ionic strength shifts the concentrations of both phase transitions to lower polymer concentrations, indicating that in presence of salt a weaker attraction is required to induce these transitions. At ϕ=0.52, just above ϕc, for dispersions without added salt, broadening of the fluid-crystalline coexistence regime, due to added PEO, results in a viscosity minimum corresponding to different size and packing density of the crystalline regions as observed earlier in Weis et al. [1]. When salt is added, the initial state for dispersions without PEO is a fluid state due to the reduction of ϕeff and the addition of a small amount of PEO leads to an increase in bulk viscosity due to the formation of large crystals for dispersions containing 10 mM NaCl and a network of small, dense crystals of size ≈10 µm when 100 mM NaCl is added. At ϕ=0.54, a result similar to ϕ=0.52 is obtained for dispersions without added salt, whereas in presence of salt, we find that the fluid/crystalline coexistence regime narrows down as the range of electrosteric repulsion decreases and the addition of PEO results in gel formation and gels become more uniform with increasing attraction strength. These investigations demonstrate how superimposed short range electrosteric repulsion and weak depletion attraction affect microstructure and flow behavior of colloidal dispersions.

Estimating Velocity Correlations Using Single Pixel PIV

In this work, we analyze the possibility of determining correlations of turbulent velocity fluctuations from PIV data with improved spatial resolution. The analysis is based on the method presented by Oldenziel et al. (2023), where a joint probability density function of the velocity at two locations is calculated from the single-pixel ensemble correlation for these locations. Synthetic PIV images are used to discuss the occurrence of random and systematic errors and to derive the number of image pairs required for a determination of the correlation coefficient with desired uncertainty, depending on the particle image density. Compared to classical window correlation, the presented method can improve the spatial resolution by about one order of magnitude if a very large number of PIV image pairs are available and/or many statistically independent points with identical flow properties can be used. As an example of application, we show the spatial distribution of a two-point correlation in a compressible turbulent boundary layer flow for a reference point near the wall.

Controlled Release Lercanidipine Tablets: A Study on Formulation and Evaluation by Wet Granulation

Lercanidipine blocks the entry of extracellular calcium into vascular and cardiac muscle cells, preventing myocardial smooth muscle contraction due to decreased intracellular calcium. This results in the dilation of coronary and systemic arteries, reducing blood pressure. This study aimed to develop and evaluate lercanidipine controlled-release tablets for oral administration using polymers like HPMC K 100M, sodium alginate, and guar gum. Lercanidipine, polymers, and diluents were sieved and mixed for 10 minutes. Granules were formed using isopropyl alcohol, dried at 60°C for one hour, and sieved. The granules were lubricated with colloidal silicon dioxide (Aerosil-200) and magnesium stearate, blended for 5 minutes, and compressed using a rotary machine (average weight: 500 mg; hardness: 5-6 kg/cm²). Bulk and tapped densities were nearly identical for all formulations. Compressibility index and Hausner ratio ranged from ?18 to 1.09-1.21, indicating good flow properties. Tablet thickness ranged from 5.82 to 5.91 mm, hardness from 5.9 to 6.3 kg/cm², and friability was less than 1.0 %W/W. Drug content was between 98-102%. The controlled-release order from dissolution data was F9 &gt; F7 &gt; F8, showing optimal release with a combination of HPMC and two natural polymers.

The three-dimensional structure of black hole accretion flows within the plunging region

ABSTRACT We analyse, using new analytical models and numerical general relativistic magnetohydrodynamic simulations, the three-dimensional properties of accretion flows inside the plunging region of black hole spacetimes (i.e. at radii smaller than the innermost stable circular orbit). These simulations are of thick discs, with aspect ratios of order unity $h/r \sim 1$, and with a magnetic field geometry given by the standard low-magnetization ‘SANE’ configuration. This work represents the first step in a wider analysis of this highly relativistic region. We show that analytical expressions derived in the ‘thin disc’ limit describe the numerical results remarkably well, despite the large aspect ratio of the flow. We further demonstrate that accretion within this region is typically mediated via spiral arms, and that the geometric properties of these spiral structures can be understood with a simple analytical model. These results highlight how accretion within the plunging region is fundamentally two-dimensional in character, which may have a number of observational implications. We derive a modified theoretical description of the pressure within the plunging region which accounts for turbulent heating and may be of use to black hole image modelling.

FSDC: Flow Samples and Dimensions Compression for Efficient Detection of DNS-over-HTTPS Tunnels

This paper proposes an innovative approach capitalized on the distinctive characteristics of command and control (C&amp;C) beacons, namely, time intervals and frequency between consecutive unique connections, to compress the network flow dataset. While previous studies on the same matter used single technique, we propose a multi-technique approach for efficient detection of DoH tunnels. We use a baseline public dataset, CIRA-CIC-DoHBrw-2020, containing over a million network flow properties and statistical features of DoH, tunnels, benign DoH and normal browsing (HTTPS) traffic. Each sample is represented by 33 features with a timestamp. Our methodology combines star graph and bar plot visualizations with supervised and unsupervised learning techniques. The approach underscores the importance of C&amp;C beacon characteristic features in compressing a dataset and reducing a flow dimension while enabling efficient detection of DoH tunnels. Through compression, the original dataset size and dimensions are reduced by approximately 95% and 94% respectively. For supervised learning, RF emerges as the top-performing algorithm, attaining precision and recall scores of 100% each, with speed increase of ≈6796 times faster in training and ≈55 in testing. For anomaly detection models, OCSVM emerges as the most suitable choice for this purpose, with precision (88.89) and recall (100). Star graph and bar graph models also show a clear difference between normal traffic and DoH tunnels. The reduction in flow sample size and dimension, while maintaining accuracy, holds promise for edge networks with constrained resources and aids security analysts in interpreting complex ML models to identify Indicators of Compromise (IoC).

Rough bed hydrodynamics under wave-current interactional flow field: double averaging approach

ABSTRACT The effect of surface wave on the double-averaged (DA) current-only flow properties is examined over two different types of rough beds comprising hemispherical elements with regular and staggered arrangements. For each case, the relative roughness spacing of p/r = 4 is maintained, where p = pitch distance and r = hemisphere height. The changes in turbulence characteristics against the water depth are analysed for superimposed surface waves propagating along the current with 1 and 2 Hz frequencies. The effect of regular and staggered roughness arrangements on different turbulence characteristics is explored. Results demonstrate that the DA stream-wise velocity decreases and increases at the outer region and within the roughness region, respectively, due to wave propagation. Owing to the surface wave, the DA intensity and form-induced intensity increase above the roughness layer and decrease within the bottom boundary layer. The values of form-induced intensities are smaller (greater) than the DA turbulence intensities at each considered flow depth within the roughness (outer) layer. For the entire flow depth, the values of DA Reynolds stress decrease due to wave interactions along a steady current. Again, the turbulence is observed to be close to isotropic for the current-only flow at the outer zone, while the flow transits to an anisotropic state with wave imposition on current. Further, the computed values of the turbulence indicator and dispersion functions are used for the identification of the level of turbulence and dispersion at each flow depth for the locations upstream and downstream of a hemisphere in the hemispherical bed.

Cellulose Acetate Microparticles Synthesized from Agave sisalana Perrine for Controlled Release of Simvastatin.

Simvastatin (SIM) is widely prescribed to treat hyperlipidemia, despite its limitations, such as a short half-life and low oral bioavailability. To overcome these drawbacks, the development of a controlled-release formulation is desirable. This study aims to develop a microparticulate system based on cellulose acetate (ACT) obtained from Agave sisalana Perrine to promote a controlled SIM release. SIM-loaded microparticles (SMP) were prepared using the solvent emulsification-evaporation method. Several parameters were evaluated, including particle size, surface charge, morphology, encapsulation efficiency, thermochemical characteristics, crystallinity, and in vitro release profile. ACT exhibited favorable flow properties after acetylation, with a degree of substitution values superior to 2.5, as confirmed by both the chemical route and H-NMR, indicating the formation of cellulose triacetate. The obtained SMP were spherical with an average size ranging from 1842 to 1857 nm, a zeta potential of -4.45 mV, and a high SIM incorporation efficiency (98%). Thermal and XRD analyses revealed that SIM was homogeneously dispersed into the polymeric matrix in its amorphous state. In vitro studies using dialysis bags revealed that the controlled SIM release from microparticles was higher under simulated intestinal conditions and followed the Higuchi kinetic model. Our results suggest that ACT-based microparticles are a promising system for SIM delivery, which can improve its bioavailability, and result in better patient compliance.