Inactive Zone Research Articles

A minimal model for vertical shear instability in protoplanetary accretion disks

The vertical shear instability is an axisymmetric effect suggested to drive turbulence in the magnetically inactive zones of protoplanetary accretion disks. Here we examine its physical mechanism in analytically tractable “minimal models” in three settings that include a uniform density fluid, a stratified atmosphere, and a shearing-box section of a protoplanetary disk. Each of these analyses show that the vertical shear instability's essence is similar to the slantwise convective symmetric instability in the mid-latitude Earth atmosphere, in the presence of vertical shear of the baroclinic jet stream, as well as mixing in the top layers of the Gulf Stream. We show that in order to obtain instability, the fluid parcels' slope should exceed the slope of the mean absolute momentum in the disk radial-vertical plane. We provide a detailed and mutually self-consistent physical explanation from three perspectives: in terms of angular momentum conservation, as a dynamical interplay between a fluid's radial and azimuthal vorticity components, and from an energy perspective involving a generalised Solberg-Høiland Rayleigh condition. Furthermore, we explain why anelastic dynamics yields oscillatory unstable modes and isolate the oscillation mechanism from the instability one.

Inflation tolerance ranges in the New Keynesian model

A number of central banks in advanced countries use ranges, or bands, around their inflation target to formulate their monetary policy strategy. The adoption of such ranges has been proposed by some policymakers in the context of the Fed and the ECB reviews of their strategies. Using a standard New Keynesian macroeconomic model, we analyze the consequences of tolerance range policies, characterized by a stronger reaction of the central bank to inflation when inflation lies outside the range than when it is close to the target, ie the central value of the band. We show that (i) a tolerance band should not be a zone of inaction: the lack of reaction within the band endangers macroeconomic stability and leads to the possibility of multiple equilibria; (ii) the trade-off between the reaction needed outside the range versus inside seems unfavorable: a very strong reaction, when inflation is far from the target, is required to compensate a moderately lower reaction within tolerance band; (iii) these results, obtained within the framework of a stylized model, are robust to many alterations, in particular allowing for the zero lower bound.

Effect of multibanded magnetic field on convective heat transport in linearly heated porous systems filled with hybrid nanofluid

The paper attempts to enhance the control of convective transport phenomena in magnetothermal devices applying a technique of multibanded magnetic field. For this demonstration, a typical cavity-like thermal system is considered involving linear heating, porous substance, hybrid nanofluid, and magnetic field. Four identical bands of magnetic fields are applied horizontally with uniform inactive zones between the bands. The transport equations of the coupled multiphysics evolving from the thermal buoyancy (due to linear heating at one sidewall and isothermal cooling at the opposite sidewall), filled porous medium, spatially intermittently active magnetic fields, and the engineered working fluid of Cu–Al2O3/water hybrid nanofluid are solved by an indigenously developed computing code. The study is conducted using the pertinent dimensionless parameters for the following ranges: Darcy–Rayleigh number (Ram = 1–104), Darcy number (Da = 10−5 − 10−1), Hartmann number (Ha = 0–70), and concentration of hybrid nanoparticles ϕ (= 0–2%). The convective phenomena are analyzed using the heatlines (for heat transport), streamlines (flow pattern), isotherms (static temperature), and the average Nusselt number (for heat transfer). The outcomes of this technique of multibanded magnetic field are rigorously compared with other established application methods of magnetic fields. It establishes different local behaviors along with an improved heat transfer. Heatline visualization reveals the definite portraits of heat flow paths depending upon parametric values. Furthermore, the presence of linear heating is in particular treated to explore the insight of linear heating (that featuring multiple heating and cooling zones along with the linear heater), utilizing the local Nusselt number and heatlines. One of the important advantages of this new technique is it is more energy-efficient particularly for the square or shallow cavity. The multibanded magnetic field shows a promising technique for the control of convective transport phenomena involving coupled multiphysics used during sophisticated applications (such as materials processing, biomedical applications, etc.).

Stellar chromospheric activity of 1674 FGK stars from the AMBRE-HARPS sample

Aims.The main objective of this project is to characterise chromospheric activity of FGK stars from the HARPS archive. We start, in this first paper, by presenting a catalogue of homogeneously determined chromospheric emission (CE), stellar atmospheric parameters, and ages for 1674 FGK main sequence (MS), subgiant, and giant stars. The analysis of CE level and variability is also performed.Methods.We measured CE in the Ca IIH&K lines using more than 180 000 high-resolution spectra from the HARPS spectrograph, as compiled in the AMBRE project, obtained between 2003 and 2019. We converted the fluxes to bolometric and photospheric corrected chromospheric emission ratio,RHK′. Stellar atmospheric parametersTeff, logg, and [Fe/H] were retrieved from the literature or determined using a homogeneous method.M⋆,R⋆, and ages were determined from isochrone fitting.Results.We show that our sample has a distribution of CE for MS stars that is consistent with an unbiased sample of solar-neighbour MS stars. We analysed the CE distribution for the different luminosity classes and spectral types and confirmed the existence of the very inactive (VI) star and very active star populations at logRHK′ < −5.1 and > − 4.2 dex, respectively. We found indications that the VI population is composed mainly of subgiant and giant stars and that logRHK′ = −5.1 dex marks a transition in stellar evolution. Overall, CE variability decreases with decreasing CE level but its distribution is complex. There appears to be at least three regimes of variability for inactive, active, and very active stars, with the inactive and active regimes separated by a diagonal, extended Vaughan-Preston (VP) gap. We show that stars with low activity levels do not necessarily have low variability. In the case of K dwarfs, which show high CE variability, inactive and active stars have similar levels of activity variability. This means that activity levels alone are not enough to infer the activity variability of a star. We also explain the shape of the VP gap observed in the distribution of CE using the CE variability-level diagram. In the CE variability-level diagram, the Sun is located in the high-variability region of the inactive MS stars zone. A method to extract the probability density function of the CE variability for a given logRHK′level is discussed, and a python code to retrieve it is provided.

Aerodynamic optimization of forward-curved blade centrifugal fan characterized by inclining bionic volute tongue

The profile and axial designs of a volute tongue have great influences on the internal flow conditions and aerodynamic performance of a forward-curved blade centrifugal fan. In order to achieve a high quality of internal flow fields and fan aerodynamic performance, we propose an inclined bionic volute tongue (IBVT) described with rotation angle and scale coefficient at the front and back walls of the volute, which varies the profile of the volute tongue and the distance between the impeller and the volute tongue in the axial direction. Meanwhile, an adaptive pseudo expected improvement matrix (APEIM) parallel multi-objective efficient global optimization (EGO) algorithm is developed by introducing a flexible number of added points for each iteration of optimization on account of the optimization problem itself. On this basis, IBVT is optimized to maximize the fan aerodynamic performance in terms of total pressure efficiency and static pressure rise by virtue of numerical simulation. The results show that the developed APEIM parallel multi-objective EGO algorithm is capable of accurately and efficiently finding the Pareto front solutions. IBVT is considered to have the effectiveness of aerodynamic performance improvement for a forward-curved blade centrifugal fan. Within the fan with IBVT, the flow fields in the axial direction become more uniform with the dimension reduction of the inactive zone around the front span. The impeller-volute tongue interaction is greatly improved with the decreases of reversed and recirculated flow coefficients. IBVT also benefits the reduction of flow losses in the volute. By adopting the analysis of variance (ANOVA), the aerodynamic performance of the fan is highly affected by the rotation angle and scale coefficient of IBVT at the front wall of the volute. This work is helpful to guide the design of the volute tongue for a forward-curved blade centrifugal fan.

Characteristics of gravity and magnetic fields and deep structural responses in the southern part of the Kyushu-Palau Ridge

The southern part of the Kyushu-Palau Ridge (KPR) is located at the conjunction of the West Philippine Basin, the Parece Vela Basin, the Palau Basin, and the Caroline Basin. This area has extremely complex structures and is critical for the research on the tectonic evolution of marginal seas in the Western Pacific Ocean. However, only few studies have been completed on the southern part, and the geophysical fields and deep structures in this part are not well understood. Given this, this study finely depicts the characteristics of the gravity and magnetic anomalies and extracts information on deep structures in the southern part of the KPR based on the gravity and magnetic data obtained from the 11th expedition of the deep-sea geological survey of the Western Pacific Ocean conducted by the Guangzhou Marine Geological Survey, China Geological Survey using the R/V Haiyangdizhi 6. Furthermore, with the data collected on the water depth, sediment thickness, and multichannel seismic transects as constraints, a 3D density model and Moho depths of the study area were obtained using 3D density inversion. The results are as follows. (1) The gravity and magnetic anomalies in the study area show distinct zoning and segmentation. In detail, the gravity and magnetic anomalies to the south of 11°N of the KPR transition from high-amplitude continuous linear positive anomalies into low-amplitude intermittent linear positive anomalies. In contrast, the gravity and magnetic anomalies to the north of 11°N of the KPR are discontinuous and show alternating positive and negative anomalies. These anomalies can be divided into four sections, of which the separation points correspond well to the locations of deep faults, thus, revealing different field-source attributes and tectonic genesis of the KPR. (2) The Moho depth in the basins in the study area is 6–12 km. The Moho depth in the southern part of KPR show segmentation. Specifically, the depth is 10–12 km to the north of 11°N, 12–14 km from 9.5°N to 11°N, 14–16 km from 8.5°N to 9.5°N, and 16–25 km in the Palau Islands. (3) The KPR is a remnant intra-oceanic arc with the oceanic-crust basement.which shows noticeably discontinuous from north to south in geological structure and is intersected by NEE-trending lithospheric-scale deep faults. With large and deep faults F3 and F1 (the Mindanao fault) as boundaries overall, the southern part of the KPR can be divided into three zones. In detail, the portion to the south of 8.5°N (F3) is a tectonically active zone, the KPR portion between 8.5°N and 11°N is a tectonically active transition zone, and the portion to the north of 11°N is a tectonically inactive zone. (4) The oceanic crust in the KPR is slightly thicker than that in the basins on both sides of the ridge, and it is inferred that the KPR formed from the thickening of the oceanic crust induced by the upwelling of deep magma in the process of rifting of remnant arcs during the Middle Oligocene. In addition, it is inferred that the thick oceanic crust under the Palau Islands is related to the constant upwelling of deep magma induced by the continuous northwestward subduction of the Caroline Plate toward the Palau Trench since the Late Oligocene. This study provides a scientific basis for systematically understanding the crustal attributes, deep structures, and evolution of the KPR.©2021 China Geology Editorial Office.

Tracking the optical mass centroid of single electroactive nanoparticles reveals the electrochemically inactive zone.

The inevitable microstructural defects, including cracks, grain boundaries and cavities, make a portion of the material inaccessible to electrons and ions, becoming the incentives for electrochemically inactive zones in single entity. Herein, we introduced dark field microscopy to study the variation of scattering spectrum and optical mass centroid (OMC) of single Prussian blue nanoparticles during electrochemical reaction. The “dark zone” embedded in a single electroactive nanoparticle resulted in the incomplete reaction, and consequently led to the misalignment of OMC for different electrochemical intermediate states. We further revealed the dark zones such as lattice defects in the same entity, which were externally manifested as the fixed pathway for OMC for the migration of potassium ions. This method opens up enormous potentiality to optically access the heterogeneous intraparticle dark zones, with implications for evaluating the crystallinity and electrochemical recyclability of single electroactive nano-objects.

Haiti-Drill: an amphibious drilling project workshop

Abstract. The Haiti region – bounded by two strike-slip faults expressed both onshore and offshore – offers a unique opportunity for an amphibious drilling project. The east–west (EW)-striking, left lateral strike-slip Oriente–Septentrional fault zone and Enriquillo–Plantain Garden fault zone bounding Haiti have similar slip rates and also define the northern and southern boundaries of the Gonâve Microplate. However, it remains unclear how these fault systems terminate at the eastern boundary of that microplate. From a plate tectonic perspective, the Enriquillo–Plantain Garden fault zone can be expected to act as an inactive fracture zone bounding the Cayman spreading system, but, surprisingly, this fault has been quite active during the last 500 years. Overall, little is understood in terms of past and present seismic and tsunami hazards along the Oriente–Septentrional fault zone and Enriquillo–Plantain Garden fault zone, their relative ages, maturity, lithology, and evolution – not even the origin of fluids escaping through the crust is known. Given these unknowns, the Haiti-Drill workshop was held in May 2019 to further develop an amphibious drilling project in the Haiti region on the basis of preproposals submitted in 2015 and their reviews. The workshop aimed to complete the following four tasks: (1) identify significant research questions; (2) discuss potential drilling scenarios and sites; (3) identify data, analyses, additional experts, and surveys needed; and (4) produce timelines for developing a full proposal. Two key scientific goals have been set, namely to understand the nature of young fault zones and the evolution of transpressional boundaries. Given these goals, drilling targets were then rationalized, creating a focus point for research and/or survey needs prior to drilling. Our most recent efforts are to find collaborators, analyze existing data, and to obtain sources of funding for the survey work that is needed.

A parametric study of the heat and mass diffusion dimensionless parameter in SOFC with DIR by lattice Boltzmann method

In the present study, the lattice Boltzmann method (LBM) is employed to study the diffusion phenomenon in solid oxide fuel cell (SOFC) with direct internal reforming (DIR). The main focus of this work is to correlate and estimate the diffusion coefficient through dimensionless numbers, i.e., Schmidt and Prandtl. This work tries to reveal the importance of reforming and electrochemical reactions on these dimensionless numbers in active and inactive zones. In addition, the effects of inlet velocity (Re number), steam-to-carbon ratio (S/C) of inlet flow, current density, and porosity were investigated to disclose their importance on diffusion phenomena. A lattice Boltzmann method is used for numerical simulation of diffusion phenomenon in porous media of anode. Our results show that the Schmidt and the Prandtl numbers could be used for high precision estimation of the diffusion process in SOFC. It is also found that the molar ratio variation in hydrogen and water is highly effective since their diffusion characteristics are significantly different from other gases. By changing in operating parameters, the variation in the Prandtl number is much greater than the reforming reactions due to electrochemical reactions. Our results indicate that the Schmidt number of hydrogen increases by 53%, and the Prandtl number decreases about 45% at the center of SOFC when the porosity decreases about 25%.

LiDAR-derived high-resolution palaeo-DEM construction workflow and application to the early medieval Lower Rhine valley and upper delta

Reconstruction of past topography in palaeo-DEMs serves various geomorphological analyses. Constructing a palaeo-DEM by stripping young elements from a LiDAR DEM can provide results for large study areas at high resolution. However, such a ‘top-down’ approach is more suited to recent periods and geomorphologically static parts of the landscape than to geomorphologically dynamic areas and periods farther back in time. Here, we explore this approach by reconstructing the early medieval (circa 800CE) topography of the Lower Rhine river valley and upper delta in Germany and the Netherlands. The large (4500km2) study area contains abundant anthropogenic terrain modification and stretches across geomorphologically active as well as inactive zones. We first removed all anthropogenic relief elements from the LiDAR DEM, using separate procedures for linear and non-linear elements. These steps were sufficient to obtain the palaeotopography of the inactive zone, characterized by inherited natural relief. Then, we reconstructed the topography and bathymetry in the fluvially-reworked active zone by incorporating geological and historical geographical information. We present and evaluate zonal averages of elevation differences between the modern and past valley floor topography in this densely populated area with complex land-use history, which allows us to approximate total anthropogenic volumetric change. Further comparisons with the modern LiDAR DEM elucidate changes in floodplain negative-relief connectivity, showing the potential importance of investing in palaeo-DEMs when assessing past river flooding. Our palaeo-DEM construction workflow is deployable at diverse spatial scales and widely applicable to other lowland areas, because of its top-down and generic nature. The relative importance of different workflow aspects depends on the time period that is targeted. Beyond a target age of 10–15ka, valley floors that are too large in area are to be considered geomorphologically dynamic and the top-down approach to palaeo-DEM construction is no longer advisable.

A Review on the Mechanism of Reservoir-Induced Seismicity for Nepalese Context

Over 90 cases of Reservoir Induced Seismicity have been recorded around the earth. The magnitude was varying from 3.0 to 6.3 on the Richter scale. A Reservoir Induced Seismicity (RIS) can increase the frequency of earthquakes in seismically active zones and cause a shock in seismically inactive zones. Nepal is situated in a seismically active zone with six large earthquakes of magnitude equal to or greater than 7.6. It increases the risk of RIS, while several storage-type hydropower projects are being proposed in Nepal. Seismic activities recorded around the Kulekhani-I reservoir could be a reservoir induced seismicity. However, consistent data of seismic events and reservoir levels during all phases of filling or drawing of water level is missing. This paper reviews the researches on seismic activities caused by reservoirs or tectonic movements, and the need for the study on the mechanism of RIS for the Nepalese context is identified.

Numerical Simulation for the Influence of EMS Position on Fluid Flow and Inclusion Removal in a Slab Continuous Casting Mold

Electromagnetic stirring (EMS) has been used to improve the steel quality in continuous casting process and EMS position is a key factor in optimizing the stirring performance. In order to clarify the issue that where to install the electromagnetic stirrer, a mathematical model, coupling electromagnetic field and fluid flow field, was developed in this paper. Three cases differing in EMS position have been investigated: the stirrer was installed above the submerged entry nozzle (SEN) port; the stirrer was installed near it; and the stirrer was installed below it. The model was validated by the comparison of electromagnetic flux density. The influence of EMS position on electromagnetic force, flow field and inclusion removal was analyzed. Index Rc was introduced to quantify the possibility of slag entrapment. The results shows that as the stirrer moves downwards, the maximum electromagnetic force increases, index Rc increases first and then turns to decrease, and the electromagnetic force causes the jet to bend more horizontally, resulting in an inactive zone when the stirrer is installed near the SEN port. Furthermore, under our computed condition, to improve the inclusion removal, the stirrer is suggested to be installed below the SEN port.

Interest rate bands of inaction and play-hysteresis in domestic investment – Evidence for the Euro Area

The interest rate is an important monetary policy tool to steer investment to safeguard price stability. Knowledge about the exact shape of the interest rate-investment nexus is thus decisive for the European Central Bank’s efficacy. This is especially so in the currently observed low interest rate environment. We first present a theoretical framework of the hysteretic impact of changes in the interest rate on macroeconomic investment under certainty and under uncertainty to investigate whether uncertainty over future interest rates in the Euro area hampers monetary policy transmission. In this non-linear model, strong reactions in investment activity occur as soon as changes of the interest rate exceed a zone of inaction, that we call ‘play’ area. Second, we apply an algorithm describing path-dependent play-hysteresis to estimate investment hysteresis using data on domestic investment and interest rates on corporate loans for 5 countries of the Euro area in the period ranging from 2001Q1 to 2018Q1. We find hysteretic effects of interest rate changes on investment in most countries. However, their shape and magnitude differ widely across countries which poses a challenge for a unified monetary policy. By introducing uncertainty into the regressions, the results do not change much which may be due to the interest rate implicitly incorporating uncertainty effects in investment decisions, e.g. by risk premia.

ДОСЛІДЖЕННЯ ПРОЦЕСУ ПЕРЕМІЩЕННЯ СИПКОГО МАТЕРІАЛУ В НЕАКТИВНІЙ ЗОНІ МІЖ ГВИНТОВИМИ СЕКЦІЯМИ

The article presents the results of theoretical and experimental studies of the process of moving bulk material in the inactive zone between hinged screw sections of a flexible screw conveyor. The influence of the gap between the edges of adjacent screw sections and the magnitude of their circular displacement on the process of continuous transportation of bulk material is presented. The results of theoretical and experimental studies are compared. This will allow choosing the optimal design, kinematic and technological parameters of the developed sectional screw working body when transporting bulk agricultural materials along curved paths, both in horizontal and inclined directions, as well as along curved paths.

Quantifying the latitudinal distribution of climate-related landforms on Mars' southern hemisphere

The focus of this work is to contribute information about possible climate-related environments on Mars from a geomorphological perspective. In order to understand the latitudinal distribution of current and former climatic environments on Mars, we applied the so-called grid-mapping approach in order to quantify the geography of 17 climate-related landforms that each indicates a particular morphoclimate at the time of their evolution. Grid-mapping combines small-scale mapping with large-scale analyses; thus, it is possible to reveal relations that are only visible from a wider perspective. While the northern mid-latitudes of Mars have already been analysed by using this method, there was no adequate equivalent for the southern hemisphere. We therefore mapped three study areas representative of the southern cratered highlands. These study areas were in Noachis Terra, Terra Cimmeria, and Terra Sirenum respectively. As the basement of the southern highlands has been formed during the Noachian, we considered all latitudes (from the equator to the pole) and climate-related landforms of all Martian eras (Amazonian, Hesperian, Noachian), in order to determine any possible morphoclimatic belts. Unlike on Earth, we could not simply transfer existing geomorphologic classes to Mars. Instead, we reclassified the landforms into H2O– and CO2-based morphologies, as both constituents have different physical properties. As a result, we detected three cumulative morphoclimatic environments, formed under the same or very similar conditions during the late Amazonian: an aeolian zone (0°-~30°S), an H2O zone (~30°-70°S), as well as a CO2 zone (≥70°S). The aeolian and H2O zones could be further subdivided into two subdivisions: an active (0°-10°S) and inactive (10°-~30°S) aeolian zone as well as a volatile/unstable (~30°S-~60°S) and permanent/stable (60°-~70°S) H2O zone. Our observations are consistent with recent models of the distribution of water-ice on the Martian surface during the Amazonian. Although we detected landforms pre-dating the Amazonian, we could not detect clear evidence for Noachian or Hesperian morphoclimatic environments, as more recent landforms cover most of the mid to high latitudes. Grid-mapping also enabled the finding of a widely undescribed crater morphology on Mars, which we term multi-annular craterlets. They are characterised by small diameters (<1 km), a multi-ring facies, and a widely flat topography (the former crater depression is entirely filled with multi-layered deposits). We suggest that they were formed during deposition and erosion of multiple layers of the latitude-dependent mantle.

Metformin Removal from Water Using Fixed-bed Column of Silica-Alumina Composite

In the last decade, traces of pharmaceutical and personal care products (PPCPs) in the nano and microgram per litre range have been reported in the water cycle; this includes surface water, wastewater, groundwater, and to a lesser extent drinking-water. Their presence in water, even at low concentrations, has raised concerns among drinking-water regulators, governments and water suppliers, regarding the potential risks to human health from exposure to traces of pharmaceuticals via drinking-water. Metformin (MF) and its transformative product, guanyl-urea, are expected to be present in aquatic environments, due to their global consumption rate. Not surprisingly, guanylurea has also been detected in surface water, groundwater, and drinking water. The toxicological studies showed that availability of MF might cause ecotoxicological effects, which suggests that MF is a potential endocrine disruptor and thus further emphasising the threat this drug could pose to our environment. Thus, many treatment methods have been suggested by many investigators to reduce the high levels of MF. Adsorption with some novel materials, for instance, showed great potential in removing MF from water in the batch processes, while very limited investigation has been done in continuous mode. Therefore, an effective adsorption process should be well implemented with use of efficient adsorbent for MF removal from water. Herein, MF adsorptive removal from water by amorphous silica-alumina (SA) composite was carried out in a fixed-bed column under the influence of various dynamic conditions (i.e., inlet solution pH, initial concentration of MF, initial flow rate, and bed-height). Initially, batch adsorption experiments were conducted to determine the adsorption kinetic parameters. Then, the obtained kinetic parameters were used to investigate the continuous adsorption inside the fixed-bed column. In the column experiments, high adsorption of MF was obtained at low flow rate, high bed height, low influent concentration, and high pH. Breakthrough behavior under the influence of various dynamic parameters was also investigated using the advection-axial dispersion model, incorporating surface and intra-particle diffusion theory to identify the key process parameters controlling the rate of adsorption. Furthermore, the unused bed length (HUNU) approach was also employed to determine the best utilization conditions for the column by correlating the unused bed (inactive zone) fraction (FH) from the column with axial Peclet number (Pex).

Mapping biogeochemically active zones in landfills with induced polarization imaging: The Heferlbach landfill

In this study, we investigate the applicability of the Induced Polarization (IP) imaging method to discriminate between biogeochemically active and inactive areas of a landfill. The elevated amount of degradable organic carbon in landfills results in the development of biogeochemical hot-spots associated with high rates of microbial activity and the generation of landfill gas and leachate as metabolic products. Our results demonstrate that the electrical conductivity is mainly sensitive to the increase in the fluid conductivity associated to leachate production and migration. Whereas images of the polarization effect, expressed in terms of the imaginary component (σ″) or the phase of the complex conductivity (ϕ), reveal the potential to characterize variations in the architecture and biogeochemical activity of the landfill. Correspondingly, biogeochemically active zones (leachable TOC contents above 1500 mg/kg dry waste) are related to high polarization values (σ″ > 10 mS/m, ϕ > 40 mrads), whereas low leachable TOC contents (<300 mg/kg dry waste) in the inactive areas are characterized by low polarization values (σ″ < 1 mS/m, 10 < ϕ < 25). Additionally, landfill sections corresponding to construction and demolition waste (CDW), associated to negligible TOC content, exhibit the lowest polarization response (σ″ < 0.1 mS/m, ϕ < 15). We prove that IP imaging is a well-suited method for landfill investigations that permits an improved characterization of landfill geometry, variation in waste composition, and the discrimination between biogeochemically active and inactive zones.

Experimental and numerical investigations on effect of blade trimming on aerodynamic performance of squirrel cage fan

The impeller of squirrel cage fan exerts great effects on the internal flow fields and fan aerodynamic performance. On the premise of maintained impeller-volute tongue distance and production cost reduction, this paper proposes a blade trimming method focusing on axial modification of blade inlet in an attempt to improve the impeller flow condition and further the aerodynamic performance of squirrel cage fan, which is divided into blade full trimming and part trimming. Aerodynamic performance tests and numerical simulations are performed to explore the effect of blade trimming on the fan aerodynamic performance and the related flow mechanisms. The results show that the blade trimming with proper trimming parameter enables the fan to achieve higher fan aerodynamic performance in terms of total pressure efficiency and static pressure rise, between which full trimming is preferable to part trimming. With the optimum full trimming of blade, the axial distributions of mass flow at the impeller inlet and outlet become more uniform. The dimension of inactive zone near the front span is decreased. On the blade pressure surface, the forces are reduced with obvious improvement of gradients near the front span and back span. A better match between impeller and volute tongue is achieved as the decreases of reversed flow coefficients at the impeller inlet and outlet and recirculated flow coefficient in the volute.

Borehole‐scale testing of matrix diffusion for contaminated‐rock aquifers

AbstractA new method was developed to assess the effect of matrix diffusion on contaminant transport and remediation of groundwater in fractured rock. This method utilizes monitoring wells constructed of open boreholes in the fractured rock to conduct backward diffusion experiments on chlorinated volatile organic compounds (CVOCs) in groundwater. The experiments are performed on relatively unfractured zones (called test zones) of the open boreholes over short intervals (approximately 1 meter) by physical isolation using straddle packers. The test zones were identified with a combination of borehole geophysical logging and chemical profiling of CVOCs with passive samplers in the open boreholes. To confirm the test zones are within inactive flow zones, they are subjected to a series of hydraulic tests. Afterward, the test zones are air sparged with argon to volatilize the CVOCs from aqueous to air phase. Backward diffusion is then measured by periodic passive‐sampling of water in the test zone to identify rebound. The passive (nonhydraulically stressed) sampling negates the need to extract water and potentially dewater the test zone. The authors also monitor active flowing zones of the borehole to assess trends in concentrations in other parts of the fractured rock by purge and passive sampling methods. The testing was performed at the former Pease Air Force Base (PAFB) in Portsmouth, New Hampshire. Bedrock at the former PAFB consists of fractured metasedimentary rocks where the authors investigated back diffusion of cis‐1,2‐dichloroethylene (cis‐1,2‐DCE), a CVOC. Postsparging concentrations of cis‐1,2‐DCE showed initial rebounding followed by declines, excluding an episodic spike in concentrations from a groundwater recharge event. The authors theorize that there are three processes that controlled concentration responses in the test zones postsparging. First, the limited back diffusion of CVOCs from a halo or thin zone of rock around the borehole contributes to the initial rebounding. Second, aerobic degradation of cis‐1,2‐DCE occurred causing declines in concentrations in the test zone. Third, microflow from microfractures contributed to the episodic spike in concentrations following the groundwater recharge event. In active flow zones, the latter two processes are not measurable due to equilibration from groundwater transport between the borehole and active flowing fractures.

IGAP-integrative genome analysis pipeline reveals new gene regulatory model associated with nonspecific TF-DNA binding affinity

The human genome is regulated in a multi-dimensional way. While biophysical factors like Non-specific Transcription factor Binding Affinity (nTBA) act at DNA sequence level, other factors act above sequence levels such as histone modifications and 3-D chromosomal interactions. This multidimensionality of regulation requires many of these factors for a proper understanding of the regulatory landscape of the human genome. Here, we propose a new biophysical model for estimating nTBA. Integration of nTBA with chromatin modifications and chromosomal interactions, using a new Integrative Genome Analysis Pipeline (IGAP), reveals additive effects of nTBA to regulatory DNA sequences and identifies three types of genomic zones in the human genome (Inactive Genomic Zones, Poised Genomic Zones, and Active Genomic Zones). It also unveils a novel long distance gene regulatory model: chromosomal interactions reduce the physical distance between the high occupancy target (HOT) regions that results in high nTBA to DNA in the area, which in turn attract TFs to such regions with higher binding potential. These findings will help to elucidate the three-dimensional diffusion process that TFs use during their search for the right targets.