Sag Tests Research Articles

Ilmenite Inclusion: A Solution towards Solid Sagging for Hematite-Based Invert Emulsion Mud

The sagging tendency of hematite in drilling mud is a common challenge occurring at high-pressure and high-temperature (HP/HT) applications. This work studies the performance of hematite-based invert emulsion mud for HP/HT conditions and provides a solution to prevent the hematite settlement using a combination of ilmenite with hematite. Practical mud formulation was utilized over a range of ilmenite/hematite ratios (0/100, 20/80, 40/60, and 50/50%) to study sagging behaviour. From the sag tests, the optimum combination proportion was determined. Thereafter, the density, emulsion stability, rheological and viscoelastic properties, and filtration conduct for the formulated mud were evaluated. The experiments were conditioned as per the standards of the American Petroleum Institute. The obtained results of sagging experiments indicated that including 50% of ilmenite mitigated the hematite settling and reduced the sag tendency towards the safe range. A slight drop (4%) in mud weight was noticed upon adding the ilmenite, whereas the emulsion stability was enhanced from 551 to 574 volts with the 50% ilmenite content. The rheology and viscoelasticity measurements showed that 50/50% combination improved the yield point (YP) by 50% with a trivial 1 cP increment on plastic viscosity (PV), hence enhancing the YP/PV ratio by 46%. Also, the gelling strength was enhanced resulting in flat rheology and better gel structure. The filtration behaviour of 50% ilmenite mud was improved compared to blank hematite as it resulted in 21, 15, and 17% reduction on the filtrated volume, filter cake weight, and thickness, respectively. This study provides a solution for hematite sagging issue at HP/HT using combined weighting agents, which contributes to enhancing the mud stability and avoiding several well control issues and related operational and technical challenges that eventually will economize the drilling cost and time.

Sagging Prevention for Hematite-Based Invert Emulsion Mud

Abstract The solids sagging in high-pressure high-temperature (HP/HT) reservoirs is a common challenge associated with hematite drilling fluids. This study provides a solution to hematite sagging in invert emulsion mud for HP/HT wells, which involves the combination of Micromax (Mn3O4) with hematite. The particles of both weighting agents were characterized to address their mineralogical features. A field formulation of the mud was used over a range of Micromax/hematite ratios (0/100, 20/80, and 30/70%) in laboratory experiments to address the sag performance and determine the optimal combination ratio. Then, density, emulsion stability, rheology, viscoelasticity, and filtration performance for the formulated mud were addressed. The tests were conditioned to 500 psi and 350 °F. The acquired results of sag tests indicated that incorporation of 30% Micromax solved the hematite sagging issue and brought the sag tendency within the recommended safe range. An insignificant reduction in mud density was observed upon the inclusion of Micromax, while the emulsion stability was obviously improved from 551 to 614 volts with the 30% Micromax mixture. The recommended 30/70% combination had almost no effect on plastic viscosity and yield point since they were increased by one unit, but the gel strength was improved resulting in flat rheology and better solids suspension capacity. The filtration behavior of the formulation with 30% Micromax was enhanced compared to pure hematite as it resulted in 10% and 14% reduction of the filtrate volume and filter-cake thickness, respectively. This study contributes to improve and economize the drilling cost and time by formulating a stabilized and distinguished-performance drilling mud using combined weighting agents at HP/HT.

Prevention of Hematite Settling in Water-Based Mud at High Pressure and High Temperature.

Hematite was recently introduced as a weighting agent in drilling fluids; however, its use has some problems because of the settlement of solid particles (solid sagging). Particularly when it comes to high-pressure high-temperature (HP/HT) wells, sagging causes inconsistency in the drilling fluid and gives rise to serious drilling operational and technical challenges. This work provides a solution to this challenge via a thorough investigation of hematite sagging in water-based mud for HP/HT applications where ilmenite is combined with hematite. The particles of both hematite and ilmenite were first characterized to address their mineralogical and textural features. Field mud formulation was employed using several ilmenite/hematite contents (i.e., 0/100, 25/75, and 50/50% ilmenite/hematite). Then, laboratory experiments were conducted to study the density, pH, and sag performance of the produced drilling fluids. From the sagging tests, the optimal ilmenite/hematite ratio was determined, and rheology, viscoelastic behavior, and filtration properties of the formulated mud were addressed. The tests were conditioned to 300 psi and 250 °F. The results showed a reduction in mud density and pH with increasing ilmenite content, as the density reduced from15 ppg with base hematite until 14.2 ppg for the 50% ilmenite mixture and the pH reduced from 10.5 to 9.3. The static and dynamic sag tests indicated that the addition of 25% of ilmenite solved the hematite-incorporated sagging issue by well placing the sag tendency within the recommended safe range. The 25/75% combination enhanced the yield point (YP) by 37% with only 1 cP increment in plastic viscosity (PV) and an insignificant effect on the gel strength. The YP/PV ratio was improved by 31% indicating better hole cleaning and solid suspension. The filtration behavior of the 25% ilmenite mixture was superior compared to that of the blank hematite because it resulted in 35, 39, and 35% reduction in the filtrate volume, filter-cake weight, and thickness, respectively. This work contributes to improving and economizing the drilling cost and time by the formulation of a stabilized and distinguished-performance drilling mud using combined weighting agents at HP/HT.

Enhancement of Static and Dynamic Sag Performance of Water-Based Mud Using a Synthetic Clay.

Fluid homogeneity and stability are of high importance as they greatly affect the fluid performance in drilling operations. Solid settlement or solid sag is a severe issue that occurs in weighted drilling muds, especially at elevated temperatures, where the weight material tends to settle down causing well control problems. This study evaluates the effectiveness of a synthetic clay (laponite) to prevent the static and dynamic sag tendency of barite-weighted drilling fluid for elevated-temperature drilling applications. Several high-density mud samples were prepared by varying the concentration of the synthetic clay. The sag tendency of the fluid samples was evaluated in the lab using dynamic and static sag tests, and the optimal concentration was determined. The impact of synthetic clay on the density, pH, and rheological properties was also studied. Moreover, the filtration properties of the developed formulation were measured using high-pressure high-temperature filtration experiments. The synthetic clay was found to be effective in reducing the static and dynamic sag tendency of barite-weighted water-based drilling fluids. 0.75 lb/bbl of laponite was adequate to eliminate solid sag at a temperature up to 250 F. This amount of laponite slightly increased the plastic viscosity by 8%, while an increase of 42% and 43–115% in the yield point and gel strength, respectively, was observed. A significant enhancement in the filtration performance was observed; the filter cake thickness and the filtrate volume were decreased by 15–20%. Additionally, the synthetic clay had an insignificant effect on the fluid density and pH.

Prevention of hematite settling using synthetic layered silicate while drilling high-pressure wells

Hematite (Fe2O3) is used as a weighting material to increase the density of the drilling fluid. Hematite has a higher density (5.05 g/cm3) compared with barite (4.2 g/cm3). Because of the high specific gravity and particle size, hematite can separate and settle down at higher temperatures (> 250 °F). The objective of this paper is to assess the usage of laponite which is synthetic layered silicate to solve the settling of hematite particles in water-based mud (WBM). Laponite was added to the WBM in different concentrations 0, 0.25, 0.5, 0.75, and 1 lb./bbl. Static and dynamic sag tests were performed to determine the optimum quantity of laponite. The viscoelastic and rheology properties were evaluated to compare between WBM-blank and WBM-laponite. The filtration test was performed at 250 °F and 300-psi pressure difference to assess the effect of adding laponite on the filter cake thickness and filtration volume. The results showed that adding 1 lb./bbl of laponite was enough to eliminate the sag issue in both vertical and 45° inclination. The sag factor was reduced from 0.594 to 0.502 at the vertical condition and from 0.62 to 0.51 for the 45° inclined condition. For the dynamic sag, the viscometer sag shoe test (VSST) decreased from 2.1 to 0.21 lb./gal after adding 1 lb./bbl of laponite. It was observed that the apparent viscosity (AV) and yield point (YP) increased by 16% and 33% after adding 1 lb./bbl of the laponite respectively, while there was no change in plastic viscosity (PV) which resulted in increasing the YP/PV ratio which is a good indication of fluid stability and better hole cleaning performance. For the filtration properties, there was no significant change in filter cake thickness and filtration volume.

Barite\u2013Micromax mixture, an enhanced weighting agent for the elimination of barite sag in invert emulsion drilling fluids

Weighting agents are mixed with the drilling mud to provide the high density required to control high-pressure high-temperature (HPHT) wells throughout the drilling operation. Solids sag occurs when the weighting agent separates from the liquid phase and settles down, causing variations in the drilling fluid density. This study evaluates barite–manganese tetroxide (Micromax) mixture to eliminate solids sag issue encountered with weighted invert emulsion drilling fluids at HPHT conditions. Micromax additive was added to barite-weighted fluids in different concentrations, 0, 15, and 30 wt% of the total weighting agent. Static and dynamic sag tests were used to evaluate the sag tendency of the new formulation under static and dynamic conditions. The performance of the new formulation was evaluated by measuring the electrical stability, density, rheological, viscoelastic, and filtration properties of the drilling fluid. The obtained results showed that Micromax additive improves drilling fluid stability by reducing the sag tendency. Adding only 30 wt% of Micromax additive eliminated barite sag issue in both dynamic and static conditions at 350 °F. 30 wt% Micromax increased the base fluid density by 5.4% and the yield point by 115% and maintained the gel strength value at 12 lb/100 ft2, while it reduced the plastic viscosity by 30%. The addition of Micromax additive improved the viscoelastic properties of the drilling fluid by maintaining a higher storage modulus to the loss modulus ratio when compared with the barite sample (in the range 4–4.5). Furthermore, 30 wt% Micromax improved the filtration performance by reducing the filtrate volume, filter cake weight, and filter cake thickness by 50%.

Prevention of Barite Sag in Water-Based Drilling Fluids by A Urea-Based Additive for Drilling Deep Formations

Barite sag is a challenging phenomenon encountered in deep drilling with barite-weighted fluids and associated with fluid stability. It can take place in vertical and directional wells, whether in dynamic or static conditions. In this study, an anti-sagging urea-based additive was evaluated to enhance fluid stability and prevent solids sag in water-based fluids to be used in drilling, completion, and workover operations. A barite-weighted drilling fluid, with a density of 15 ppg, was used with the main drilling fluid additives. The ratio of the urea-based additive was varied in the range 0.25–3.0 vol.% of the total base fluid. The impact of this anti-sagging agent on the sag tendency was evaluated at 250 °F using vertical and inclined sag tests. The optimum concentration of the anti-sagging agent was determined for both vertical and inclined wells. The effect of the urea-additive on the drilling fluid rheology was investigated at low and high temperatures (80 °F and 250 °F). Furthermore, the impact of the urea-additive on the filtration performance of the drilling fluid was studied at 250 °F. Adding the urea-additive to the drilling fluid improved the stability of the drilling fluid, as indicated by a reduction in the sag factor. The optimum concentration of this additive was found to be 0.5–1.0 vol.% of the base fluid. This concentration was enough to prevent barite sag in both vertical and inclined conditions at 250 °F, with a sag factor of around 0.5. For the optimum concentration, the yield point and gel strength (after 10 s) were improved by around 50% and 45%, respectively, while both the plastic viscosity and gel strength (after 10 min) were maintained at the desired levels. Moreover, the anti-sagging agent has no impact on drilling fluid density, pH, or filtration performance.

Classifications in Brief: The Schenck Classification of Knee Dislocations.

Classifications in Brief: The Schenck Classification of Knee Dislocations.

Low voltage ride through capability enhancement in a grid‐connected wind/fuel cell hybrid system via combined feed‐forward and fuzzy logic control

Fault ride through (FRT) capability is an essential practice as per the present grid code demands for grid-connected renewable energy-based distributed energy resources. Studies on FRT capability for grid-connected hybrid systems are rarely found. This study considers a wind energy conversion system and a fuel cell system interconnected at a common dc bus. It proposes a new feed-forward-based FRT control scheme for the inverter control where new current references in dq -axis frame are derived by tracking the positive sequence power. The newly derived references are fed forward to the input of the current regulator of the voltage source inverter. Second, fuzzy logic-based current controllers are suggested to improve the tracking capability of the current references in the inverter control scheme so as to enhance the FRT capability of the hybrid system as a whole. The proposed feed-forward-fuzzy control scheme for achieving an enhanced FRT capability is compared with the conventional dq current control and feed-forward FRT control for various grid voltage sag tests, where the performance of the combined feed-forward-fuzzy control is found better. The validation of the proposed FRT control scheme is performed in MATLAB-Simulink environment.

New Ferritic Stainless Steel for Service Temperatures up to 1050 °C Utilizing Intermetallic Phase Transformation

A large number of thermodynamic simulations has been used to design a new Nb-Ti dual stabilized ferritic stainless steel with excellent creep resistance at 1050 °C through an optimal volume fraction of Laves (η) phase stabilized by the alloying elements Nb, Si and Mo. By raising the dissolution temperature of the phase, which also corresponds to the onset of rapid grain growth, the steel will better maintain the mechanical properties at higher service temperature. Laves phase precipitates can also improve creep resistance through precipitation strengthening and grain boundary pinning depending on the dominant creep mechanism. Sag tests at high temperatures for the designed steel showed significantly better results compared to other ferritic stainless steels typically used in high temperature applications at present.

Mitigation of barite sagging during the drilling of high-pressure high-temperature wells using an invert emulsion drilling fluid

Sagging of particles is one of the most critical issues when drilling deep oil and gas wells especially when the hole angle is greater than 30°. Accumulation of cuttings at the bottom of the hole around the drilling bit as a result of barite sagging cause severe problems such as the loss of well control. Temperature has a major effect on barite sagging so there is a need to develop a new drilling fluid formulation that can prevent barite sagging under different geometries of hole path and high temperatures (greater than 300 °F).The objective of this study is to evaluate the effect of using an organophilic phyllosilicate (OP) as an anti-sagging additive to prevent barite sagging in an invert emulsion drilling fluid (IEDF) at high temperature (350 °F). Static sag tests were conducted at vertical and inclined (45°) positions at 350 °F. Dynamic sag tests were performed at 120 °F. The second objective is to determine the optimum concentration of OP and evaluate the effect of the selected concentration on the rheological and filtration properties of the IEDF at 350 °F.The results show that the optimum amount of OP for preventing barite sagging at 350 °F in both vertical and inclined positions is 1.5 g. Adding 1.5 g of the OP prevents barite sagging under dynamic conditions and enhances the rheological properties by increasing the yield point plastic viscosity ratio. The OP enhances the suspension capability of the drilling fluid at low shear rate (3 rpm).

Histoplasma Urinary Antigen Testing Obviates the Need for Coincident Serum Antigen Testing.

Serum and urine antigen (SAg, UAg) detection are common tests for Histoplasma capsulatum. UAg detection is more widely used and reportedly has a higher sensitivity. We investigated whether SAg detection contributes meaningfully to the initial evaluation of patients with suspected histoplasmosis. We reviewed 20,285 UAg and 1,426 SAg tests ordered from 1997 to 2016 and analyzed paired UAg and SAg tests completed on the same patient within 1 week. We determined the positivity rate for each test. Of 601 paired specimens, 542 were concurrent negatives and 48 were concurrent positives (98% agreement). Medical records were available for eight of 11 pairs with discrepant results. UAg was falsely positive in six instances, truly positive once, and falsely negative once. These findings support using a single antigen detection test, rather than both UAg and SAg, as an initial screen for suspected histoplasmosis. This aligns with the current practice of most physicians.

P187 Estimating cost savings by introducing a reflex Hepatitis B virus screening algorithm in a sexual health service

Background/introduction BASHH recommends that screening for HBV infection may be with HBcAb, with reflex HBsAg testing in HBcAb-positive patients. False negative HBcAb (eg in acute HBV infection or with low assay sensitivity) is rare. At the time our laboratory did not routinely perform reflex HBsAg testing, placing the onus on clinicians, many of whom therefore requested both tests simultaneously (with redundant sAg tests being performed in the presence of a negative cAb). We wished to audit the extent of this practice and estimate cost savings by introducing reflex testing. Aim(s)/objectives This was a retrospective case notes review of patients for whom HBcAb had been requested between 01/01/15 and 01/05/15. The cost of performing HBsAg testing was estimated at £3.60 per test. Methods There were two hundred patients with HBcAb results: 110 (55%) male; median age 32 (IQR 26–39) years; 9 (4.5%) HIV-infected. Twenty-two (11%) tested HBcAb-positive of whom 5 (2.5%) were HBsAg-positive, 16 (8.0%) HBsAg-negative and 1 (0.5%) not tested for HBsAg. Of the HBcAb-positive individuals, requesting details were available for 10 cases: for 8/10 both HBsAg and HBcAb were requested initially. Of 178 (89.0%) HBcAb-negative individuals, HBsAg was performed for 49 (24.5%); all were HBsAg-negative. Across the Trust, 11,500 HBcAb tests were requested in 12 months. Assuming 89.0% HBcAb-negativity, the cost of testing 24.5% of these patients for HBsAg would almost reach £10,000. Results Reducing HBsAg testing in HBcAb-negative individuals would provide savings. Reflex laboratory HBsAg should be implemented for HBcAb-positive patients.

Power quality performance of energy-efficient low-wattage LED lamps

Light-emitting Diode (LED) lamps are more versatile and energy efficient compared with conventional light sources. This paper investigates two main problems related to power quality, namely, the harmonic generation from LED lamps and the effect of voltage sags on LED lamps. Laboratory tests on various LED lamps are conducted and the electrical characteristics of LED lamps are tapped under different conditions. Frequency domain analysis is then performed to investigate the generated harmonics. Then, voltage sag sensitivity analysis is performed by obtaining signals from a photo sensor, the different parts of a lamp ballast, and input voltage. The analysis includes the effects of varying sag depth and voltage sag duration. The findings are compared with the SEMI F47 standard curve, which predicts the effects of voltage sags on lamp performance. Experimental results show that the LED lamps produce a considerable amount of current harmonics. Moreover, different types of LED lamps were found to produce different levels of current harmonic depending on the ballast configuration. This harmonic distortion can be reduced by combining various types of LED lamps. Voltage sag tests show that all the tested lamps are sensitive to sag depth and sag duration.

Experimental Investigation of the Effect of Calcium Lignosulfonate on Adsorption Phenomenon in Surfactant Alternative Gas Injection

Fractional flow analysis confirms the advantages of surfactant alternative gas injection (SAG) in enhanced oil recovery, but an adsorption phenomenon that has been affected by several factors, weakens the effectiveness of SAG injection. In this study, the effects of sacrificial agent, gas phase, and surfactant concentration on adsorption density on silica mineral were investigated by static and dynamic adsorption experiments. A series of SAG tests were performed to examine the effect of injection rates and presence of Calcium Lignosulfonate (CLS) on oil recovery. Also, variation of effluent sodium dodecyl sulfate (SDS) concentration during SAG test was examined. Spectrophotometric method based on the formation of an ion-pair was used in all experiments for determination of SDS concentration. The results of adsorption experiments show that SDS adsorption density on silica was reduced when nitrogen was imposed instead of using methane. It can be reduced with addition of CLS as sacrificial agents and amount of adsorption reduction increases as concentration increases. Flooding experiment results show that SAG injection increase ultimate recovery up to 10% in comparison with water alternative gas (WAG) injection. Increasing viscosity of gas phase and its trapping in porous media results a decrease in the mobility of gas and an increase in oil recovery. Stability of formed foam in porous media is rate-depended and higher SDS adsorption was observed at first cycle of SAG injection due to high solid/liquid interaction. Using CLS slightly increases the ultimate oil recovery, while it decreases the adsorption density of SDS about 22 percent during the SAG test.

Experimental evaluation of DG's dynamic voltage support capability improving short‐term voltage stability on power system loads

AbstractHigh DG penetration will seriously degrade the short‐term voltage stability of the load in bulk power systems. Simulation results in previous studies by the authors have shown that the dynamic voltage support (DVS) capability of a DG improves stability, but experimental evaluation does not yet exist. This paper presents the effects of the DVS capability of a DG on an experimental circuit consisting of an induction motor, a resistance load, and a compensation capacitor behind a reactance. First, an experimental setup that causes voltage instability without DVS is set up. Second, an improvement in DG inverter control is made in order to achieve a low‐voltage ride‐through (LVRT) capability and DVS capability, and the DG's performance is confirmed by voltage sag tests. Finally, the tests on the experimental setup demonstrate that the DVS capability greatly improves the short‐term voltage stability of power system loads, and the experimental results agree well with the simulation results. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(2): 28–36, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20914

系統負荷の短時間電圧安定性を改善する分散型電源の動的電圧維持機能の実験的評価

High DG penetration will seriously degrade the short-term voltage stability of the load in bulk power systems. Simulation results in previous studies by the authors have shown that the dynamic voltage support (DVS) capability of a DG improves stability, but experimental evaluation does not yet exist. This paper presents the effects of the DVS capability of a DG on an experimental circuit consisting of an induction motor, a resistance load, and a compensation capacitor behind a reactance. First, an experimental setup that causes voltage instability without DVS is set up. Second, an improvement in DG inverter control is made in order to achieve a low-voltage ride-through (LVRT) capability and DVS capability, and the DG's performance is confirmed by voltage sag tests. Finally, the tests on the experimental setup demonstrate that the DVS capability greatly improves the short-term voltage stability of power system loads, and the experimental results agree well with the simulation results. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(2): 28–36, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20914

Stainless Steels for Exhaust Lines

Exhaust lines of cars have been strongly evolving during the last decade to meet the various requirements of the automotive industry and the new environment regulations. This development tends to favour stainless steel grades to replace cast iron for the exhaust manifold and aluminized low carbon steel for pipes and mufflers. Among the various stainless steel grades, the proportion of ferritic grade increases for the hot part of the exhaust system as its price is lower and more stable than austenitic or refractory grades, and as it exhibits a better resistance to cyclic oxidation.A large and rapid development of stainless ferritic grades has been based on Ti and Nb stabilization. Adding niobium presents many advantages for corrosion resistance, deep‐drawability, and mainly creep resistance at high temperature. The paper is focused on stainless steel with 14 wt% chromium, stabilized with Nb. Intermetallic precipitation is studied after a 100 h holding time at different temperatures (sag tests). It is shown that, depending on the test temperature and on the chemical composition of the steel, Fe2Nb or Fe2Nb3 intermetallic particles can precipitate, which affects the creep resistance: Fe2Nb3 being more stable at higher temperature. Some impacts on the alloy design dedicated to exhaust line application are presented as a conclusion of the study.

Yellow Passion Fruit RindA Potential Source of Low-Methoxyl Pectin

Yellow passion fruit (Passiflora edulis f. flavicarpa Degener) rind pectic substances were fractionated with water, ammonium oxalate, and dilute acid solutions. The extracted pectins were rich in anhydrogalacturonic acid and had a low degree of methyl esterification. Moreover, their acetyl groups and neutral sugar contents were relatively low. Furthermore, a low amount of proteinaceous material was also found within them. Their gelling ability and viscoelastic properties as evaluated by the SAG and small amplitude oscillatory shear tests, respectively, were comparable to those of a commercial citrus low-methoxyl pectin. Hence, yellow passion fruit rind occurs as a potentially good source of naturally low-methoxyl pectin.

Ｌａ２Ｏ３添加Ｍｏ板における長大結晶粒積層組織の形成と機械的性質

Molybdenum sheets (trade name: TEM) having elongated coarse-grain structures were developed. The grain structures were controlled by hot and cold rolling under high total reduction ratio (εt) and recrystallization treatment at 2070K of sintered Mo body with lmass% of La2O3.The recrystallization temperatures of La2O3-doped Mo sheets which were examined in terms of Vickers hardness and optical microstructure were higher than those of pure-Mo and TZM (Mo-0.56Ti-0.086Zr-0.016C by mass%) sheets. In particular, that of the La2O3-doped Mo sheet with high εt of 99.1 % was about 1830K, 400K higher than that of the pure-Mo sheet.The deformation resistance of TEM sheets having elongated coarse-grain structures, which was examined by sag tests at 1470K to 2070K, were superior to those of the pure-Mo and TZM sheets with equiaxial grains. In particular, deformation resistance was improved at aspect ratios (L/W) exceeding 20. Sag value of TEM sheets with L/W=150 after sag test for 36ks at 2070K was less than 1/100 that of pure-Mo sheet and less than 1/60 of TZM sheet.The shock resistance of TEM sheets with L/W=150 at room temperature, which was examined by the falling-weight impact test, was superior to that of the pure-Mo sheet with equiaxial grains.