Drain Configuration Research Articles

Can local drain flow measurements be utilized to improve catchment scale modelling?

Tile drains constitute a shortcut from agricultural fields to surface water systems, significantly altering the transport pathways and fate of nitrate during transport. A correct representation of tile drainage flow is thus crucial for estimating nitrate load at the catchment scale and to identify optimal locations for N-mitigation measures. Drainage is a local process, controlled by local properties and drain configurations, which are rarely known for individual fields, making drainage flow and transport a challenging task in catchment scale models. This study tests the potential for improving drainage flow dynamics at catchment scale, by utilising local drainage flow measurements in a spatial calibration scheme. A distributed hydrological model, MIKE SHE, for the agricultural-dominated Norsminde catchment (145 km2) in Denmark, was calibrated using spatially distributed surrogate parameters (pilot points) to represent heterogeneity in the soil (top 3 m) and the deeper geology below 3 m. The model was calibrated using hydraulic heads, stream discharge, and measured drainage flow from eight drain catchments. Drain measurements were very important in guiding the calibration of top 3 m and subsurface pilot points located in the drainage fields, showing that drain flow hold information on both local (shallow) and regional (deeper) flow patterns. Contrarily, pilot points located outside the drained fields were mainly sensitive to the hydraulic head measurements and the summer water balance of the stream discharge on a catchment scale. Consequently, incorporation of the drain data improved local performance, but did not improve the parameterization and drain description of the entire catchment. Exploitation of the drain flow information is thus difficult beyond the drain catchments, and other approaches are needed to extrapolate and exploit the local data.

Low-Voltage LDO Regulator Based on Native MOS Transistor with Improved PSR and Fast Response

In this paper, a low-voltage low-dropout analog regulator (ALDO) based on a native n-channel MOS transistor is proposed. Application of the native transistor with the threshold voltage close to zero allows elimination of the charge pump in low-voltage regulators using the pass element in a common drain configuration. Such a native pass transistor configuration allows simplification of regulator design and improved performance, with supply voltages below 1 V, compared to commonly used regulators with p-channel MOS transistors. In the presented design of ALDO regulator in 180 nm CMOS X-FAB technology, an output voltage of 0.7 V was achieved with an output current of 10 mA and a supply voltage of 0.8 V. Simulation results show that despite the low supply voltage, output voltage spikes do not exceed 70 mV at the worst technology corner when output current transients from 100 µA to 10 mA. Under such conditions, stable operation and power supply rejection PSR = 35 dB were achieved with an output capacitance of 0–500 pF. The proposed regulator allows to push the limit of ALDO regulator applications to voltages below 1 V with only slight degradation of its performance.

Influence of 4 drain configurations on fluid dispersal and retrieval in an instillation model

To describe and compare the pattern of fluid dispersal and retrieval in a novel instillation therapy system. In vitro experimental study. A 10 cm2 square model was constructed using plastic sheeting secured to plexiglass, with a wound infusion catheter and Jackson-Pratt (JP) active suction drain positioned in 4 configurations: parallel, perpendicular, diagonal, and opposite. Fluid was instilled using the wound infusion catheter, allowed to dwell for 10 min, and retrieved using the JP drain. Two surface area calculations were made using imaging software: coloration with diluted methylene blue (MB) on photos, and filling with diluted contrast on fluoroscopic images. Fluid retrieval was recorded. Statistical analysis was performed using a mixed-effects linear model (p < .05). Configuration influenced fluid dispersion within the model (p=.0001); the diagonal configuration had the greatest surface area coverage (mean ± SD; 94.5 ± 2.4%) and the parallel configuration had the lowest surface area coverage (60.2 ± 2.9%). A dwell period increased fluid dispersal by an average of 4.0 ± 0.8% (p < .0001). Fluid retrieval exceeded 16.7 ± 1.5 mL (83.5 ± 7.5% volume instilled) for all configurations and was 0.5 ± 0.1 mL (2.5 ± 0.5% volume instilled) greater for MB than contrast agent (p < .0001). Perpendicular or diagonal configurations and low-viscosity fluid maximized fluid dispersion and retrieval. Wound instillation therapy involves delivering lavage fluid or medications to a closed wound space. This is feasible using a wound-infusion catheter and active suction drain. Configuration should be considered to optimize fluid dispersal and retrieval when planning instillation therapy.

Advanced practice-aided tile drain configuration: A solution to achieving environmentally sustainable agricultural production

Alternatives to conventional crop production practices are needed to achieve environmental sustainability. Because tile-drained crop production systems in the Midwestern United States are one of the single largest contributors to environmental degradation, we explored alternative tile drain configurations by changing the tile spacing and depth of tile-drained fields in central Illinois and then by evaluating comprehensively the impacts of different tile drain configurations on crop productivity and environmental sustainability using the Root Zone Water Quality Model 2 (RZWQM2). An analytic hierarchy process (AHP), which is a multicriteria decision analysis (MCDA) tool, was used to evaluate the optimum tile spacing and depth scenario. The model simulations and AHP tested three management schemes designated as “agricultural productivity” (AP), “environmental sustainability” (ES), and “advance in technology” (AT). The schemes were designed based on three criteria: operational cost, crop profit, and environmental control. Analysis showed that deeper tiles and narrower tile spacing resulted in decreases in flow and nitrate loss from runoff, seepage (SP), and lateral flow (LF), and increases in tile flow, total nitrate loss, and crop yields. On the basis of MCDA, the AP management scheme resulted in higher CP and total nitrate loss, whereas opposite outcomes were generated by the ES management scheme. Under the AT management scheme, higher ranked scenarios resulted in higher CP and lower total amounts of nitrate entering streams. Our analysis indicates that the AT scheme can simultaneously enhance crop production and ES through advances in tile drainage water treatment.

SiC MOSFET C-V Curves Analysis with Floating Drain Configuration

SiC MOSFETs have already replaced silicon-based device in power applications, even if some technological issues are still not solved. Among others, the complex traps distribution at SiC/SiO2 interface is of foremost importance. Interface traps affect the overall device behavior, modifying channel mobility and introducing hysteresis. In this work, the capacitance behavior, when the Drain terminal is floating, is studied through numerical analysis. The effects of traps distribution and its properties on such curves has been studied along with temperature effects. Experimental curves are carried out at various temperatures and compared to the same trends of numerical results.

New Measurement Method for Self-Heating in Silicon-on-Insulator MOSFETs Based on Shared Series Resistance

A new method using temperature dependent shared series resistance in a pair of devices with common drain configuration is proposed to measure self-heating (SH) in advanced MOSFETs. The proposed measurement technique depends on the intrinsic series resistance and is not limited to the spatial proximity between the heater and the sensor. The developed method demonstrated on the silicon-on-insulator (SOI) MOSFETs reveals that the more accurate SH assessment can be obtained compared to other methods that are sensitive to the distance from heat source. Furthermore, the extraction of intrinsic series resistance allows to quantify the process-induced variability of the contact resistance.

Reducing off-state leakage current in dopingless transistor employing dual metal drain

In this paper a new configuration for dopingless transistor is presented for preventing the off-state tunneling from channel to drain. In this work, workfunction engineering has been performed at drain electrode of the device. For this, drain electrode metal is divided into two sections. Workfunction of the drain section near the gate is kept at relatively higher value than the other section. This approach increases the tunnel barrier formed at the gate-drain interface which prevents the carries to tunnel from channel to drain in the off-state (VGS = 0.0 V, VDS = 1.0 V). Employing dual metal at drain electrode gives better control over channel which results in significant improvement in the electrical performance of the junctionless transistor. The IOFF for proposed dual metal drain (DMD) configuration is reduced by 5 orders which aids to improve ION/IOFF ratio by 4 orders as compared to conventional for gate length 20 nm. The subthreshold slope and drain induced barrier lowering are also reduced by 4% and 35% respectively. The DMD device also exhibits reduced intrinsic capacitances (Cgg and Cgd). To evaluate the performance, comparative analysis of the proposed device has been performed with dual metal gate and conventional transistors which have yielded considerable improvements. The gate length (LG) scaling down to 5 nm has also been performed for the DMD configuration to demonstrate its advantages over conventional counterpart.

Dual-gate operation and carrier transport in SiGe p–n junction nanowires

We investigate carrier transport in silicon–germanium nanowires with an axial p–n junction doping profile by fabricating these wires into transistors that feature separate top gates over each doping segment. By independently biasing each gate, carrier concentrations in the n- and p-side of the wire can be modulated. For these devices, which were fabricated with nickel source–drain electrical contacts, holes are the dominant charge carrier, with more favorable hole injection occurring on the p-side contact. Channel current exhibits greater sensitivity to the n-side gate, and in the reverse biased source–drain configuration, current is limited by the nickel/n-side Schottky contact.

Centrifuge model study on geogrid reinforced soil walls with marginal backfills with and without chimney sand drain

The objective of this paper is to investigate the performance of geogrid reinforced soil walls with panel facing using marginal backfill with and without chimney sand drain subjected to seepage. A series of centrifuge model tests were performed at 40 gravities using a 4.5 m radius large beam centrifuge facility available at IIT Bombay. The results revealed that a geogrid reinforced soil wall with low stiffness geogrid and without any chimney drain experienced a catastrophic failure due to excess pore water pressure that developed in the reinforced and backfill zones at the onset of seepage. In comparison, a soil wall reinforced with stiff geogrid layers was found to perform effectively even at the onset of seepage. Provision of chimney sand drain effectively decreased pore water pressure not only at the wall toe but also at mid-distance from toe of the wall and thereby resulted in enhancing the wall performance under the effect of seepage forces. However, a local piping failure was observed near the toe region of the wall. The observed centrifuge test results were further analysed by performing seepage and stability analyses to evaluate the effect of thickness of sand layer in a chimney drain. An increase in thickness of sand layer in chimney drain was found to improve the discharge values and thereby enhancing the factor of safety against piping near the toe region. Based on the analysis and interpretation of centrifuge test results, it can be concluded that marginal soil can be used as a backfill in reinforced soil walls provided, it has geogrid layers of adequate stiffness and/or proper chimney drain configuration.

Bias-Point Calculation and Parameter Extraction Using EKV Compact MOS Model Equation

ABSTRACTThe main aim of this tutorial is to apprise readers about parameter extraction and bias-point calculation using Enz–Krummenacher–Vittoz compact metal oxide semiconductor (MOS) model equation. The model equation has been applied to an NMOS (N-channel metal oxide semiconductor) transistor case present on the P-substrate and P-well. Two cases are considered to show parameters extraction and bias-point calculation for a modified/unmodified value of the transistor threshold voltage. After presenting equation simplification for the two cases, different parameter extraction methods are discussed. Then a common drain configuration biased by a resistance is simulated to match by hand-calculated results.

Multi-Scale Modeling of Self Heating Effects on Power Consumption in Silicon CMOS Devices

This work pursues a multi-scale modeling approach to combine interconnect and device level simulation in order to study the effects of carrier self-heating and thermal transport on device performance. More specifically, this work will focus on power consumption and heat dissipation in silicon CMOS technology. As device dimensions decrease to the nanometer scale, current density in the device active regions and the circuit interconnects increases [4]. This increase in current density leads to substantial increases in operating temperatures in critical regions of nano-scale electronic devices. We have already shown these effects in n-channel MOSFETs [2], and will continue to explore how this phenomenon affects p-channel MOSFETs and CMOS circuits. This paper presents the methodology used for the study, multi-scale results from the n-channel MOSFET simulations, and preliminary results from the device level p-channel MOSFET simulation. The modeling approach combines an electro-thermal device simulation with a thermal transport solver at the circuit level. The electrical simulation solves Poisson's equations self-consistently coupled with an ensemble Monte Carlo to determine internal electric fields and model electron and hole transport in the device [3]. The thermal simulation solves the energy balance equations for acoustic and optical phonons and uses the phonon energy to determine the lattice temperature [5]. The electro-thermal solver couples these two processes by introducing temperature dependent scattering to the carrier transport solver. Thermal transport can be modeled in a variety of ways: phonon Monte Carlo simulations are necessary for modeling extreme nano-scale and hot-carrier devices, energy balance modeling is used in this study to model thermal transport at the device level, and the Joule heating method commonly used in commercial device simulators is used in this study to model thermal transport at the interconnect level. The thermal modeling in the device and the interconnects is coupled using the device structure itself as an interface: the electro-thermal simulator provides Joule heating terms throughout the device to be used in the Joule heating simulator which in turn gives the temperature profile in the interconnects to be used as a boundary condition in the electro-thermal solver. These simulations are repeated in a self-consistent loop until convergence is achieved [2]. This modeling approach has been successfully applied to n-channel MOSFET devices and the results have been confirmed using a novel experimental approach. Two identical MOSEFTs in either common source or common drain configuration can be biased such that one device is in saturation and one device is in cut-off or sub-threshold region. The device in saturation heats up and the device in sub-threshold is used as a sensor; the temperature in the sensor can be determined using the subthreshold slope [2]. Confirming the simulation results with experimental results for the temperature in the subthreshold device substantiates the accuracy of the methodology for determining the temperature throughout the device [2]. This methodology, now verified by comparison with experimental results for n-channel MOSFETS, will be applied to the study of CMOS circuits.

Three-Port Model of a Modern MOS Transistor in Millimeter Wave Band, Considering Distributed Effects

Distributed nature of an MOS transistor becomes significant in high frequencies, especially in the millimeter wave band. Two types of distributed effects are encountered in an MOS transistor: the distributed effect along the transistor channel, referred as nonquasi static (NQS) effect, and the distributed effect along the gate finger. We denote the former as lateral distributed effect and the later as longitudinal distributed effect (LDE). Lateral distributed effect has been studied in many works and has been considered either accurately or approximately in the available MOS small-signal models. However, LDEs have not accurately been accounted for, except for few works in which an MOS transistor has been analyzed using transmission line approach to derive two-port ${Y}$ parameters of the transistor. Unfortunately, the two-port distributed model is not useful when the transistor is used in common gate, common drain, or cascode configurations. In this paper, we have developed a new three-port distributed model of an MOS transistor to accurately capture the LDEs. Furthermore, the proposed model can be used in conjunction with new Berkeley short-channel IGFET model (BSIM) radio frequency (RF) small-signal models, such as BSIM4.7 and BSIM6. To evaluate the proposed model, we have used Taiwan Semiconductor Manufacturing Company 90 nm RF-CMOS technology parameters. Our results show that LDE is considerably more significant than NQS effect in millimeter wave band, in the case of a short channel MOS transistor with long gate finger. This reveals the importance of LDEs in RF MOS transistor models, especially in millimeter wave band applications.

Generalized Analysis of Random Common-Mode Rejection Performance of CMOS Current Feedback Instrumentation Amplifiers

The generalized CMRR analysis of the CMOS current feedback instrumentation amplifier (CFIA), in drain and source feedback configurations (termed DCFIA and SCFIA), is developed by focusing on the input stage. The random CMRR for processes (CMRRP) of the CFIAs are derived as a function of the transistor dimensions, small-signal and operating parameters, as well as the process-dependent mismatch factors, to gain insights into the statistical CMRR characteristics, which enables better design optimization. Simplification of the analysis based on practical constraints yields closed-form CMRRP equations that reveal different design considerations for the two CFIA configurations. For example, while the DCFIA relies on the matching of the input transistors, the matching of the drain load transistors is critical for CMRRP enhancement of the SCFIA (this criterion differs from established design practice). The analysis also reveals that unlike the SCFIA, the DCFIA features a direct tradeoff between noise and CMRRP. The integrity of the analysis is validated by comparison with simulations of various published CFIAs designed in a 0.35- $\mu$ m CMOS process.

Novel Multiplexer Design Using Multi-State Spatial Wavefunction-Switched (SWS) FETs

In this paper, we propose a multiplexer design based on use of a twin channel and twin drain spatial wavefunction-switched field-effect transistors (SWSFETs). SWSFET comprises of vertically stacked coupled quantum wells devices, which are the channels, where depending on the gate voltage only one of the channels is in conduction mode. Using SWSFET in multi-channel and single drain configuration operates as a multi-valued logic device. 2:1 and 4:2 multiplexer designs are proposed which are compatible with current CMOS technology and with all SWSFET. Both designs lead to greater than 4X reduction in transistor count. Ngspice simulation of circuits is also presented.

Evaluation of the performance and space requirement by three different hybrid constructed wetlands in a stack arrangement

Lack of space for a wastewater treatment plant is a common problem in many areas, especially in dense cities. Constructed wetlands (CWs) are efficient natural systems; however, they require large areas. The aim of this study is the development of a compact CW design for the treatment of domestic wastewater, the Duplex-CW: a hybrid system with a stacked design (vertical flow CW (VFCW) on top of a horizontal flow filter (HFF)). The performance of three different configurations of Duplex-CW, called fill and drain, stagnant batch and free drain, was compared. The VFCWs operated differently with the intention of creating different oxygen conditions, whereas the HFFs were operated identically. The Duplex-CWs were subjected to three different wastewater strengths, corresponding to designs of 7.9, 3.4 and 2.6m2PE−1. The highest strength was treated with and without artificial aeration of the VFCW of each configuration. The contribution to the total removal of each compartment (VFCW and HFF), the effects of the use of artificial aeration, the solids accumulation, above- and below-ground biomass and the footprint requirements of the three configurations tested were determined. The fill and drain configuration performed better than the other two, the VFCW compartment being more active in the treatment than the HFF. It achieved an area of 2.6–3.4m2PE−1 and it needed 2–3 times lower area than what a single VFCW would have needed to reach similar total nitrogen effluent concentrations. The Duplex-CW did not contribute to the footprint reduction, for other parameters (e.g. COD, TSS and total phosphorus).

Reduction of off-state drain leakage in InGaAs-based metal-oxide-semiconductor field-effect transistors

Off-state drain leakage current has been investigated for InGaAs-based metal-oxide-semiconductor field-effect transistors with different drain configurations, InGaAs, and InP, respectively. The introduction of an InP drain presents a lower leakage current compared to InGaAs drain devices. From temperature dependent measurements, the leakage current mechanisms have been differentiated, and the role of drain direct band-to-band tunneling, as well as gate-induced drain leakage, has been identified.

Modeling the impact of nitrogen fertilizer application and tile drain configuration on nitrate leaching using SWAT

Recently, the Soil and Water Assessment Tool (SWAT) was revised to improve the partitioning of runoff and tile drainage in poorly drained soils by modifying the algorithm that computes the soil moisture retention parameter. In this study, the Revised SWAT model was used to evaluate the sensitivity and long-term effects of different nitrogen (N) application rates and tile drain spacing (SDRAIN) and depths (DDRAIN) on nitrate-nitrogen (NO3-N) losses through tile drains. Monitoring data for the 1983–1996 period measured on three experimental plots on a poorly drained Webster clay loam soil (fine-loamy, mixed, superactive, mesic Typic Endoaquoll) in southern Minnesota was used. Sensitivity analysis covered the 1983–1996 period and long-term simulations were made for the 1915–1996 period. Sensitivity analysis showed a decrease in tile flow as DDRAIN decreased and/or SDRAIN increased. The predicted NO3-N losses in tile drain decreased by 16% (from 33.8 to 28.4kgha−1) and 14% (from 34.0 to 29.4kgha−1) when SDRAIN was increased by 122% (from 27 to 60m) and 40% (from 1.5 to 0.9m), respectively. However, NO3-N losses were decreased by 67% (from 33.8 to 11.1kgha−1) when N application rate was decreased by 50% (from 200 to 100kgha−1). Long-term simulations results indicated that much greater reductions in NO3-N losses can be achieved with reduction in the N application rates than with changing the tile drain spacing and depth. Reductions in NO3-N losses were consistent with the results reported using the Agricultural Drainage and Pesticide Transport (ADAPT) model, which was developed specifically for understanding effects of tile drainage on water quality in the Upper Midwest U.S. Overall, results from sensitivity analysis and long term simulation indicated that Revised SWAT can be used to adequately evaluate the effects of tile drain configurations on drainage and associated NO3-N losses.

Comparison of the performances of DRAINMOD-NII and ADAPT models in simulating nitrate losses from subsurface drainage systems

Adequate knowledge on the movement of nitrate-nitrogen (NO3-N) under different subsurface (tile) drain configurations and management practices in the U.S. Midwest is essential for developing remedial measures for reducing hypoxic conditions in the Gulf of Mexico. In this study, DRAINMOD-NII, a daily time-step soil carbon (C) and N model, was calibrated and validated for subsurface drainage and associated NO3-N losses, and crop yield. Long term (1983–1996) monitoring data measured on three experimental plots under continuous corn (Zea mays L.) with conventional tillage practice at the University of Minnesota's Southern Research and Outreach Center near Waseca, southern Minnesota was used for this purpose. Nash-Sutcliffe efficiency (NSE), Percent Error (PE) and Index of agreement (d) were used for assessing the model performance. DRAINMOD-NII predicted monthly subsurface drainage matched well with measured data during calibration (NSE=0.81, PE=−7.8% and d=0.94) and validation (NSE=0.67, PE=−0.7% and d=0.88) periods. Performance of DRAINMOD-NII for predicting monthly NO3-N losses in subsurface drainage was also good for both calibration (NSE=0.64, PE=0.8%, and d=0.85) and validation (NSE=0.62, PE=−5.3%, and d=0.83) periods. DRAINMOD-NII predicted average (1983–1992) annual corn relative yield (93%), a ratio of crop yield in a year to the long-term average crop yield, was close to the observed relative yield (92.5%). DRAINMOD-NII simulation results were also compared and contrasted with those obtained by the Agricultural Drainage and Pesticide Transport (ADAPT) model with the same dataset. Both models performed equally well in predicting monthly subsurface drainage. However, DRAINMOD-NII performed slightly better in predicting monthly NO3-N losses and annual N budget, in addition to showing potential to simulate the effects of excess and deficit water stresses on crop yield. Studies comparing performances of different drainage models in the U.S. Midwest are useful to select an appropriate model for devising various strategies for reducing NO3-N losses from subsurface drainage systems, and thereby minimizing hypoxic conditions in the Gulf of Mexico.

The radiographic appearance of split Blake drains: what you see is not necessarily what you get

Two types of Blake chest drains are used by our cardiac surgeons for management of their patients after thoracic surgery. The drain can be longitudinally split by the surgeon resulting in a limb of the drain in each thoracic cavity. A split flat Blake drain has two radiopaque limbs and a split round Blake drain has a radiopaque limb and a less radiopaque limb. To describe the radiographic appearance of these drains and promote their accurate radiologic identification and description. We conducted a retrospective review of the ability of our radiologists to correctly identify the radiographic appearance of the two devices. We identified 48 cases; 30 contained two radiopaque limbs and 18 had a radiopaque and a less radiopaque limb. In 25 of the 30 (83%) cases the configuration of two radiopaque limbs was correctly identified; however, in 0 of 18 (0%) cases was the configuration of a radiopaque and a less radiopaque limb correctly identified. By improving awareness of different Blake drain configurations and appearances this study aims to promote proper identification, accurate reporting, and reduced cognitive errors arising from Blake drain misidentification.

Full-scale experiments on a beach drainage system: hydrodynamic effects inside beach

An extensive full-scale laboratory investigation on a two-dimensional physical model of a beach drainage system (BDS) was performed at “Grosser Wellen-Kanal” of Hannover, Germany. This research deals with the hydrodynamic aspects of a beach equipped with a BDS, while the morphodynamic aspects of the study are discussed in a companion paper. Knowledge of both the hydrodynamic and the morphodynamic behaviours of a drained beach allows the definition of the main design criteria. The adopted BDS was constituted by four corrugated pipes. Several drain configurations in static and dynamic conditions were considered, paying attention to water table oscillations, drains and groundwater regime and drainage discharge induced by the system start-up. The main results indicate a rise in the unsaturated beach and the presence of a hydraulic disconnection in the groundwater–drain system. The analyses yield useful hydrodynamic information influencing the general system efficiency.