Depletion Process Research Articles

THE MOST IMPORTANT AREAS OF MODERN WATER ENGINEERING AND THE NEED FOR ITS IMPROVEMENT

Water construction began with the birth of mankind. But early man did the need for Sewerage system. In the era of STD and urbanization, it has become a serious problem. The processes of pollution and depletion of water resources are developing widely. Proposed to combine supplementing existing water intakes protected them from contamination using a barrier technology.

Mechanism of oxides reduction during bubbling of copper-smelting slags by CO–CO<sub>2</sub> gas mixtures

The paper suggests a mechanism of simultaneous oxide reduction from multicomponent copper-smelting slags during their bubbling with CO–CO2 reducing mixtures and provides a numerical algorithm developed to implement this mechanism as a mathematical model. The first feature of the suggested mechanism is a statement that the total speed of the overall reduction process is determined by CO consumption during its interaction with oxygen ions formed in slag oxide dissociation. The second feature is a statement about equilibrium achieved between slag, alloy and gaseous phase according to the system oxidizing potential reached at every instant. The paper demonstrates a satisfactory agreement between calculated and experimental data obtained when reducing industrial coppersmelting slags at 1300 °С and СО/СО2 = 4, 6, 156, and using the first-degree kinetic equation regarding the difference between initial and equilibrium CO contents in the gaseous phase. A generalized kinetic constant of the multicomponent slag reduction reaction rate is calculated as k = 2.6·10–7, moles CO /(cm2 · sec·%) at 1300 °С. It is shown that during industrial multicomponent slag reduction, reduction speed of copper (I) oxide and magnetite are high and close to maximal ones as early as at the first minutes of slag bubbling with reducing gas. At the same time, for Fe(II), lead and zinc oxides they are low at the first minutes of the process, and increase gradually to reach their maximum, and then decrease again up to near-zero values as the supplied gas and melt come to equilibrium. Generally, oxide reduction speed naturally decreases with approaching to equilibrium between the initial gas and liquid phases, and this should be taken into account when designing continuous slag depletion processes.

Melting and metasomatism/refertilisation processes in the Patagonian sub-continental lithospheric mantle: A review

The large amount of geochemical variability in peridotitic and pyroxenitic xenoliths exhumed by Eocene to present-day magmas in Patagonia provides a unique opportunity to investigate the depletion and enrichment processes affecting the lithosphere in proximity of subduction settings and their relationships with magmatism. In this study, a review of the geochemical features of the Patagonian ultramafic xenoliths coupled with new SrNd isotopic data on clinopyroxene separates from representative suites enabled us to delineate the main melt extraction and enrichment (metasomatism vs. refertilisation) processes acting in these sub-continental lithospheric mantle (SCLM) portions. Our findings show that clinopyroxenes and orthopyroxenes in Patagonian harzburgites/lherzolites lie on two discrete Al2O3/Mg# trends and record variable partial melting degrees (1–30%), progressively decreasing southward, where the mantle domains experienced melt extraction in the past. The occurrence of both negative and positive correlations between (La/Yb)N, SrN, and Al2O3 in clinopyroxenes suggests that large part of the SCLM beneath Patagonia was affected by both metasomatic (low melt-fluid/rock ratio) and refertilisation (high melt-fluid/rock ratio or long-lasting low melt-fluid/rock interaction) processes, while a few portions - particularly in Southern Patagonia - were devoid of significant enrichment processes. A comprehensive study of the major/trace element composition and rare earth element patterns of clinopyroxene from both cumulitic and mantle xenoliths led us to hypothesize that tholeiitic enrichment was followed by infiltration of transitional/alkaline agents in the Northern and Central Patagonian SCLM. The percolation of melts with transitional affinity can be identified in some Central Patagonian localities. In Southern Patagonia clinopyroxenes record a slight interaction with alkaline and proto-adakitic agents; the latter occurred at Cerro Fraile, the locality nearest the trench. The SrNd xenolith isotopic signature led to speculation that enriched and depleted mantle components interacted variably in the SCLM domain beneath Patagonia. This work suggests that a detailed and comprehensive study of ultramafic xenoliths can help identify the evidence produced by magmatic events occurring at the surface, as both a serial affinity and a temporal sequence.

The Geopolitics of Social Reproduction and Depletion: The Case of Iraq and Palestine

AbstractThis article explores the relationships between social reproduction, depletion, and geopolitical processes, drawing on two case studies: Iraq and Palestine. It underlines the importance of social reproduction to geopolitical processes and of particular geopolitical contexts to how states intervene in social reproduction, with differential implications for depletion. It argues that Iraqi state measures targeting social reproduction have sought to organize and instrumentalize the life of Iraqi citizens in the service of postcolonial state building and war-making, whilst, by contrast, Israeli state measures targeting Palestinian social reproduction have largely sought to erase Palestinian life in line with a settler colonial logic.

Non-equilibrium phase behavior in gas condensate depletion experiments

Full diameter core depletion tests are performed in this study to investigate the influence of depletion rate on the production of gas and condensate. Experimental results confirm that the gas recovery of the fast-depletion test is lower than that of the slow-depletion test. On the contrary, without the consideration of the fluid flow in porous media, the condensate recovery of the fast-depletion test is higher than that of the slow-depletion test.Non-equilibrium phase behavior is claimed to explain this abnormal behavior. The non-equilibrium model is adopted in this paper based on the components’ transfer rates between oil and gas phases. In addition, with the consideration of the compositional change in gas-condensate production, a numerical model is built to simulate the depletion process. Based on the comparison between the simulation and experimental results, the influence of non-equilibrium phase behavior on gas-condensate production is analyzed. If the depletion rate is relatively high, the heavy components of the gas-condensate system tend to be produced within the gas phase instead of condensing inside the core due to incomplete vapor-liquid separation. As a result, more condensate is acquired from the fast-depletion test.

Control of entomological diversity in agricultural systems

Our planet is undergoing the sixth wave of mass extinction of biota. So, according to the World Wildlife Fond (WWF) data, the living planet index for vertebrates (an indicator of global biodiversity) has decreased by almost 60% from 1970 to 2014. Ecologists are concerned because of the depletion of insect populations, as far as they make up about two thirds of all biota species, and are essential for maintaining the stability of ecosystems and providing environmental services. Currently, about one-third of all types of insects are under threat of extinction. In the last 30 years, the loss of insect biomass is about 75%. This is observed even in habitats with low levels of anthropogenic impact. The strategy of conservation of biodiversity requires, first of all, quantitative and comparative assessment in ecosystems of different levels. Such studies are carried out regularly for regional and global ecosystems of different nature. Biodiversity indicators have been developed and tested; databases have been compiled, which allows controlling the dynamics of population depletion process. But the state of entomological diversity in local acroecosystems (at the level of farms, separate agrocenoses) is researched not deep enough. Particularly in them biota falls under powerful anthropogenic influences. To evaluate the species richness of local ecosystems, such indices as Shannon-Weaver, Simpson, Macintosh, etc., are developed, each of which has its advantages and disadvantages. Scientific researches on substantiation of methods of system assessment of the state of the entomofauna of agricultural territories were insufficient, which determined the relevance of our work. The goal of the work was to substantiate the methods of controlling the state of the species diversity of insects in local agroecosystems using the Shannon-Weaver index. The analysis of the generalized results of faunal studies of agroecosystems showed that the entomological species diversity of crops included 167 species of 8 orders. The most abundant species were the Coleoptera order representatives (58 species) followed by Lepidoptera (35 species), Hemiptera (34 species), the least frequent were Homoptera (4 species) and Thysanoptera (2 species).It is known that the current species variety of different agrocenoses is primarily determined by the agricultural crop. Therefore, a differentiated assessment of the index indicator was conducted for each agricultural crop separately. For calculations, the results of faunal studies in each culture were used. The value of the Shannon-Weaver index is 2.4924. According to the Standard of Ukrainian Companies 73.10-37-694:2008 these data indicate a very high diversity of species, which is distinctive for natural ecosystems and lea lands. The reason of the large entomological diversity of the crop is due to the fact that wheat has long been cultivated in Ukraine, has a significant number of wild relatives, phytophagous insects from which were able to switch their nutrition to the cultivated culture. Studies have shown that the Shannon-Weaver index differentiates quite accurately the diversity of the entomofauna of different crops. Thus, faunal studies of maize and rape crops showed that the species abundance of entomofauna cultures varies by 2 taxa. Correspondingly, the index for maize was 1,6140 and for rape — 1,5849. The ability to reflect the current state of the entomofauna, simplicity of calculation, allows us to recommend the Shannon-Weaver index for controlling biodiversity of agrocenoses. The results of our field studies indicate a significant impoverishment of entomological biodiversity of agricultural landscapes, which is confirmed by numerous literary evidences of the global biodiversity crisis.

Nuclear-Magnetic-Resonance Study on Oil Mobilization in Shale Exposed to CO2

SummaryReservoirs in the Qian 34 10 rhythmic layer of the Qianjiang Basin are shale oil reservoirs with intersalt sediments. During the natural depletion and development process, production rate of oil decreases rapidly. Water injection and CO2 injection are potential technologies for enhanced oil recovery (EOR) in shale. Because of high salt content in formations, unsaturated water dissolves salt and damages reservoirs. CO2 does not react with salt, and CO2 injection does not damage reservoirs. Moreover, CO2 could enter the micropores of the reservoir rocks and mobilize oil by diffusion, extraction, and swelling mechanisms. To verify oil mobilization in the shale exposed to CO2, exposure experiments based on nuclear magnetic resonance (NMR) were conducted in this study.NMR T2 spectrum could reflect the oil in place and be used to calculate the oil content of rock with low permeability. In this study, 10 fresh shale samples (from six depths) were analyzed, and the oil contents were determined using NMR T2 spectra. Two of the shale samples with high oil contents were selected for the CO2-exposure experiment. At a temperature of 40°C and a pressure of 17.5 MPa, the fresh shale samples were exposed to CO2, and the NMR T2 spectra obtained were used to continuously determine the oil content of the shale. The oil mobilization in the shale exposed to CO2 was determined.The results of the NMR T2 spectra showed that the NMR volume fractions of the remaining oil in seven fresh shale samples were above 10%. The recovery of the S5# shale exposed to CO2 was 51.2% after 8 days, whereas that of the S9# shale was 55.8% after 6.1 days. These results indicated that more than half of the shale oil was mobilized during the relatively long exposure time after CO2 injection. NMR T2 spectroscopy results also showed that oil in all pores could be mobilized as the exposure time increased.This study showed the quantitative results of the CO2-injection method and EOR in a shale oil reservoir of the Qianjiang Basin. All conclusions support starting a CO2-EOR pilot project in the shale oil reservoir with intersalt sediments with ultralow permeability.

Analysis of Groundwater Resources in the Kyrgyz Republic

The relevance of this article is beyond doubt since the groundwater resources of the Kyrgyz Republic are very important for providing the population with drinking water. The article provides an analysis of groundwater reserves in the Kyrgyz Republic. The volumes and conditions of groundwater are given. On the territory of Kyrgyz Republic over its entire area, natural underground “lakes” are widespread. Determined the depth of groundwater reserves. Groundwater distribution flows were described. Groundwater contamination by nitrates and nitrites has been identified. Unsystematic creation of frequent water intakes, lack of monitoring of their operation can lead to aggravation of the situation with groundwater, lead to increased pollution and depletion processes. Since this topic has previously been little studied, the novelty of this article lies in the fact that the authors analyzed the causes of pollution of groundwater and offered their own ways to solve this problem.

Pore network model for retrograde gas flow in porous media

Gas well deliverability in retrograde gas reservoirs is affected by the appearance of a liquid phase near the wellbore when the bottom-hole pressure is below the dew point. At low enough pressure gradients, the liquid phase may bridge the pore throats, blocking the gas phase flow, leading to what is known as condensate blockage. If the pressure gradient is above a critical value, the capillary forces cannot block the gas flow and the condensate bridges are displaced. Gas production can be estimated using reservoir-scale simulation of the retrograde gas flow near producing wells using relative permeability curves that take into account the different physical phenomena and their dependence on local pressure, temperature and pressure gradient (capillary number). Pore-scale simulators can be used to model retrograde gas flow through porous media and to determine the gas and liquid phases relative permeability curves as a function of different flow parameters. Here, a fully-implicit isothermal compositional pore-scale network model is presented for retrograde gas flow in porous media at high capillary number, at which capillary forces are neglected. The flow pattern in each capillary changes from a single-phase gas flow to a two-phase core-annular flow regime when the pressure and the fluid composition reach a critical condition based on the thermodynamics of the fluid mixture. Newton's method is used to solve the non-linear flow and thermodynamics equations to calculate the pressure distribution and the flow rate of each component through the network. The model was used to predict gas-liquid relative permeability at high capillary number from a depletion process in a 2D network. The results show the evolution of the condensate saturation at different conditions and how the gas permeability falls abruptly at a certain condensate saturation.

Integrated droplet microfluidic device for magnetic particles handling: Application to DNA size selection in NGS libraries preparation

We present an innovative droplet microfluidic device based on integrated soft-magnetic structures allowing extraction, redispersion and depletion processes of magnetic particles. Following a numerically-assisted conception, the device was at first fabricated and experimentally characterized, showing reliable and efficient magnetic particles extraction with a low carryover of the initial matrix (<3.5%), in a broad range of dispersed phase viscosities (between 1 and 15 mPa·s) and particles loads (between 0.1 μg and 1.5 μg). Its functionalities were successfully exploited to perform DNA size selection processes for NGS libraries preparation. The device achieved final concentrations and size distributions comparable with conventional methods, demonstrating compatibility with downstream sequencing and providing improvements in automation, throughput and workflow simplification. Finally, this device represents a universal solution for high throughput multi-steps magnetic solid phase extraction workflows in a wide range of applications, e.g. immunoassays, nucleic acids and proteins purification, and sample preparation.

Palmitate로 유도한 골격근 세포의 ER stress에서 RYR channel억제가 미토콘드리아 생합성에 미치는 효과

PURPOSE: This study was to investigate the functional role of ryanodine receptor(RYR) on palmitateinduced metabolic changes which related with endoplasmic/sarcoplasmic reticulum stress(ER) and mitochondria function.<BR> METHODS: To examine the function of RYR on palmitate-induced ER stress and mitochondria dysfunction, 100uM palmitate was treated with C2C12 cell. Palmitate-induced reactive oxygen species (ROS) formation was measured by DCFDA fluorescence dye. ER Ca<SUP>2+</SUP> level was measured by using thapsigargin-induced ER Ca<SUP>2+</SUP> release method which was detected by Flou-4 am, Ca<SUP>2+</SUP> dye. palmitateinduced mitochondria potential was measured by TMRM dye. ER stress protein IRE1-alpha expression, phosphorylation, and mitochondria byosynthesis related protein, PGC1 alpha, ACC and UCP2 were analyzed by western blotting. All parameters were compared between control cell, palmitate - treated cell and palmitate and dantrolene - treated cell.<BR> RESULTS: Palmitate significantly increases intracellular ROS and ER stress marker and also increases ER Ca<SUP>2+</SUP> depletion. Palmitate decreases mitochondrial potential and mitochondria biosynthesis related protein expression and phosphorylation. Beside of these results, dantrolene treated C2C12 cells significantly ameliorated palmitate-induced ER Ca<SUP>2+</SUP>depletion, ER stress marker increase and mitochondrial potential decrease compared with control cell. These results suggest RYR channel was involved with palmitate-induced ER depletion, mitochondria dysfunction and ER Ca<SUP>2+</SUP> level coincides with mitochondria potential and function.<BR> CONCLUSIONS: These results suggest that palmitate increase ER Ca2+ depletion and decrease mitochondria function. RYR channel could involve palmitate-induced ER Ca2+ depletion process and plays a pivotal role in palmitate-induced the progression of ER stress and mitochondria dysfunction.

Multicore bi-layer gold-coated SPR-based sensor for simultaneous measurements of CFC and HCFC

Global warming is an alarming issue in our daily life. As we know that CFCs and HCFCs have a great impact on ozone depletion and global warming process. So, there must be a cheaper way to detect CFCs and HCFCs from refrigerant products like refrigerator, aerosols, air-conditioner, etc. So, for the very first time, this paper proposes a novel highly sensitive dual-core bi-layer gold-coated surface plasmon resonance (DB-SPR)-based photonic crystal fiber (PCF) for sensing CFCs and HCFCs in the field of chemical and biosensing. The analysis is assumed at 20[Formula: see text]C (293 K) for the concentration level of CFCs and HCFCs ranging between 20% and 80%. The entire numerical evaluation process is done by using finite element method (FEM) with a full vectorial software named COMSOL V-5.1 by examining the number of mesh elements of 228,120 which has better flexibility in the fabrication process. The proposed model can prove itself better than any other models by the justification of the major optical parameters, such as birefringence (B[Formula: see text]), coupling length (L[Formula: see text]), confinement loss ([Formula: see text]), transmittance (T[Formula: see text]), transmittance variance (T[Formula: see text]), power fraction (P[Formula: see text]), amplitude sensitivity (S[Formula: see text]), wavelength sensitivity (S[Formula: see text]), figure of merit (FOM), resolution (Rl[Formula: see text]), resonance (R2), etc. which respectively corresponds to their maximum performance profiles of 0.038, 40 [Formula: see text]m, 1140 dB/cm, −180 dB, 410 dB/RIU, 51%, −3200 RIU[Formula: see text], 30450.43 nm/RIU, 1300, 1.25[Formula: see text]×[Formula: see text]10[Formula: see text], 0.98712. So, it is evident that proposed SPR PCF can be a tough competitor in the field of biosensing and chemical sensing as well as gas sensing.

Characteristic response of striatal astrocytes to dopamine depletion.

Astrocytes and astrocyte-related proteins play important roles in maintaining normal brain function, and also regulate pathological processes in brain diseases and injury. However, the role of astrocytes in the dopamine-depleted striatum remains unclear. A rat model of Parkinson's disease was therefore established by injecting 10 μL 6-hydroxydopamine (2.5 μg/μL) into the right medial forebrain bundle. Immunohistochemical staining was used to detect the immunoreactivity of glial fibrillary acidic protein (GFAP), calcium-binding protein B (S100B), and signal transducer and activator of transcription 3 (STAT3) in the striatum, and to investigate the co-expression of GFAP with S100B and STAT3. Western blot assay was used to measure the protein expression of GFAP, S100B, and STAT3 in the striatum. Results demonstrated that striatal GFAP-immunoreactive cells had an astrocytic appearance under normal conditions, but that dopamine depletion induced a reactive phenotype with obvious morphological changes. The normal striatum also contained S100B and STAT3 expression. S100B-immunoreactive cells were uniform in the striatum, with round bodies and sparse, thin processes. STAT3-immunoreactive cells presented round cell bodies with sparse processes, or were darkly stained with a large cell body. Dopamine deprivation induced by 6-hydroxydopamine significantly enhanced the immunohistochemical positive reaction of S100B and STAT3. Normal striatal astrocytes expressed both S100B and STAT3. Striatal dopamine deprivation increased the number of GFAP/S100B and GFAP/STAT3 double-labeled cells, and increased the protein levels of GFAP, S100B, and STAT3. The present results suggest that morphological changes in astrocytes and changes in expression levels of astrocyte-related proteins are involved in the pathological process of striatal dopamine depletion. The study was approved by Animal Care and Use Committee of Sun Yat-sen University, China (Zhongshan Medical Ethics 2014 No. 23) on September 22, 2014.

Assessment of the residual life of the high-temperature elements of the turbine rotors through modeling the reduction of the metal continuity

Calculation and experimental estimates of the residual life of steels P2M and EI415 of two strength levels (H and B) are carried out using two methods, the new one and the traditional. The loading was carried out for 300 thousand hours under conditions similar to those in which the metal operates in the zone of blade attachment in the rim of the disk of the first stage of medium-pressure rotors of K-300-240 LMZ and KhTZ turbines. When evaluating the residual life, a gradual decrease in stresses due to creep was taken into account by distinguishing several stages with conditionally constant stresses. According to the new methodology, the residual life was estimated by a change in the metal super-continuity at each stage 47 = ц/п + 1, where u/ is the continuity, n is the crack formation index; whereas in the traditional method the relative damage Р is estimated according to the principle of linear summation of damage (LSP). It is shown that the time dependences P and 47 obey the logarithmic law, while the metal of the fbrgings В (high strength) in all cases had a greater resource compared to the fbrgings H (low strength). For the first time, the process of resource depletion was considered by analyzing the sum of two functions: 47 + P = 1. It is shown that for R2M steel this amount is less than unity; for steel EI415 it is equal to or greater than unity. Proceeding from the literature data on the differences that follows from using LSP rule for a relatively viscous and brittle metal, we suggested that deviations from unity are attributed to the error in estimating the resource according to the LSP principle. Therefore, the result obtained by the new method should be recognized as more accurate. Taking into account the use of samples with a particularly deep sharp notch in which the brittle crack development is guaranteed by the proposed methodology, the new principle of calculating the residual life can be used in determination of the resource for any type of the parts made of the metal subjected to brittle fracture during operation under creep conditions.

Impact of shale matrix mechanical interactions on gas transport during production

Shale gas has played an increasingly important role in world energy supply in recent years. The gas transport process in the shale matrix is particularly important as it affects the long-term production behavior of shale gas. The shale matrix consists of inorganic minerals and embedded organic matter with mass transfer influenced by mechanical interactions. We develop a micro-scale discrete coupled model to explicitly account for mass transfer and mechanical interactions, and how these interactions affect the gas transport characteristics of both components. Specifically, the model comprises organic matter embedded within inorganic minerals. The proposed model is implemented and solved within the framework of COMSOL Multiphysics (Version 5.4). The model is first verified against the results of a desorption-diffusion-seepage coupled experiment and then extended to field scale. It is found that the impacts of gas pressure and effective strain are different for the gas seepage in inorganic minerals and gas diffusion in organic matter. Gas pressure may enhance the permeability of the inorganic phase due to the gas slippage effect while compactive effective strain decreases permeability during the gas depletion process. For gas diffusion in the organic matter, surface diffusion decreases and effective diffusion coefficient increases with declining gas pressure. While the impacts of effective strain on the effective diffusion are dependent on the external boundary conditions, the effective diffusion coefficient is lower than the initial value under constant stress conditions and larger than the initial value under constant volume conditions. The proposed model provides a complementary method to conventional continuum dual-media approaches and provides a clear understanding of the interactions between the two components. Field-observed oscillatory gas production data is readily history-matched and key mechanisms explained with the proposed approach presented in this work.

The Status Quo Theory of Depletion Does Not Explain the Israeli Parole Decisions

Danziger et al. (2011a) showed that the parole decisions of an Israeli court of parole are influenced by judicially extraneous factors such as the time of day the case is heard. It was suggested in the paper that the cyclical parole frequencies could be explained by a status quo theory of depletion, but it did not test the theory in the data. We first show that the statistical model used in Danziger et al. (2011a) can be interpreted as a behavioral model of a depletion process. Under this interpretation, the status quo theory is inconsistent with the reported results. The statistical model however imposes a restrictive assumption of depletion processes that are uniform across judges. Individual specific depletion processes, which is suggested by theory and supported by the data, affect the measurement of a key test statistic. Allowing for judge specific depletion processes, the evidence is more mixed, but we find overall little support for the status quo theory of depletion.

Spectral and orbital survey of medium-sized meteoroids

Aims. We investigate the spectra, material properties, and orbital distribution of millimeter- to decimeter-sized meteoroids. Our study aims to distinguish the characteristics of populations of differently sized meteoroids and reveal the heterogeneity of identified meteoroid streams. We verify the surprisingly large ratio of pure iron meteoroids on asteroidal orbits detected among mm-sized bodies. Methods. Emission spectra and multi-station meteor trajectories were collected within the AMOS network observations. The sample is based on 202 meteors of −1 to −14 magnitude, corresponding to meteoroids of mm to dm sizes. Meteoroid composition is studied by spectral classification based on relative intensity ratios of Na, Mg, and Fe and corresponding monochromatic light curves. Heliocentric orbits, trajectory parameters, and material strengths inferred from empirical KB and PE parameters were determined for 146 meteoroids. Results. An overall increase of Na content compared to the population of mm-sized meteoroids was detected, reflecting weaker effects of space weathering processes on larger meteoroids. The preservation of volatiles in larger meteoroids is directly observed. We report a very low ratio of pure iron meteoroids and the discovery of a new spectral group of Fe-rich meteors. The majority of meteoroids on asteroidal orbits were found to be chondritic. Thermal processes causing Na depletion and physical processes resulting in Na-rich spectra are described and linked to characteristically increased material strengths. Numerous major and minor shower meteors were identified in our sample, revealing various degrees of heterogeneity within Halley-type, ecliptical, and sungrazing meteoroid streams. Our results imply a scattered composition of the fragments of comet 2P/Encke and 109P/Swift-Tuttle. The largest disparities were detected within α-Capricornids of the inactive comet 169P/NEAT and δ-Aquarids of the sungrazing 96P/Machholz. We also find a spectral similarity between κ-Cygnids and Taurids, which could imply a similar composition of the parent objects of the two streams.

Study on salt precipitation induced by formation brine flow and its effect on a high-salinity tight gas reservoir

For the tight gas reservoir with high salinity formation water, the flow of formation brine may cause salt precipitation and thus promote scale formation. Salt deposition and the accompanying scale formation as well as swelling and shrinkage of clay minerals may cause blockage of the pore and throats, which will significantly reduce permeability and the subsequent gas production rate. In this study, the influence of salt precipitation/dissolution on the physical properties of a tight gas reservoir is studied. Core analyses, core flooding tests, core evaporation tests, and microscopic visual flooding inspections are carried out on core samples extracted from the Shahejie Formation. To simulate the depletion production process in the subsurface, brine flow characteristics are studied by core flooding tests with pressure reduction at a formation temperature of 115 °C and with the change of pressure ranging from 30 to 1 MPa. The potential changes in physical properties including permeability, porosity, pore radius, pore size distribution, and surface area are analyzed by core evaporation tests. To show the brine flow and geometry of salt deposits in the pore structure, visual brine flooding is observed under high magnification microscope. Photos of the pore structure at different stages of salt precipitation are recorded. The results reveal that salt dissolution/precipitation has a significant impact on flow-through characteristics, and it can be divided into three stages during the depletion process. The damage of salt to the core permeability could reach more than 90%, and it increases gradually with the reduction of porosity and initial permeability and the increase of specific area. The maximum formation damage caused by salt precipitation is realized when the salt crystal size and pore throat diameter are close in size. The semi-empirical Carman-Kozeny equation together with porosity and grain diameter is used to estimate the permeability after precipitation.

Parametric emulation and inference in computationally expensive integrated urban water quality simulators

Water quality environmental assessment often requires the joint simulation of several subsystems (e.g. wastewater treatment processes, urban drainage and receiving water bodies). The complexity of these integrated catchment models grows fast, leading to potentially over-parameterised and computationally expensive models. The receiving water body physical and biochemical parameters are often a dominant source of uncertainty when simulating dissolved oxygen depletion processes. Thus, the use of system observations to refine prior knowledge (from experts or literature) is usually required. Unfortunately, simulating real-world scale water quality processes results in a significant computational burden, for which the use of sampling intensive applications (e.g. parametric inference) is severely hampered. Data-driven emulation aims at creating an interpolation map between the parametric and output multidimensional spaces of a dynamic simulator, thus providing a fast approximation of the model response. In this study a large-scale integrated urban water quality model is used to simulate dissolved oxygen depletion processes in a sensitive river. A polynomial expansion emulator was proposed to approximate the link between four and eight river physical and biochemical river parameters and the dynamics of river flow and dissolved oxygen concentration during one year (at hourly frequency). The emulator scheme was used to perform a sensitivity analysis and a formal parametric inference using local system observations. The effect of different likelihood assumptions (e.g. heteroscedasticity, normality and autocorrelation) during the inference of dissolved oxygen processes is also discussed. This study shows how the use of data-driven emulators can facilitate the integration of formal uncertainty analysis schemes in the hydrological and water quality modelling community.

Reset integral control for improved settling of PID-based motion systems with friction

We present a reset control approach to improve the transient performance of a PID-controlled motion system subject to Coulomb and viscous friction. A reset integrator is applied to circumvent the depletion and refilling process of a linear integrator when the solution overshoots the setpoint, thereby significantly reducing the settling time. Robustness for unknown static friction levels is obtained. The closed-loop system is formulated through a hybrid systems framework, within which stability is proven using a discontinuous Lyapunov-like function and a meagre-limsup invariance argument. The working principle of the proposed reset controller is analyzed in an experimental benchmark study of an industrial high-precision positioning machine.