Drain Series Research Articles

A Case Study Watershed of Siraspur Delhi

In many nations, watershed development is a critical component of rural development and natural resource management initiatives. A watershed is a kind of common pool resource that consists of a geohydrological unit that drains to a common location through a series of drains. All regions on the planet are part of one or more watersheds, and even small land fragments act as watersheds (for this purpose a case study on VILLAGE SIRASPUR, DELHI is also a part of MICROWATERSHEDS IN DELHI). Watershed management is problematic because watershed systems include a variety of competing uses, thus any gain or cost will be distributed unevenly across users. Theories based on common research suggest that managing complex watersheds would be challenging, and that success will be restricted to isolated, actively aided micro watershed programmes with a social organisation emphasis. The simplest way to encourage community action is at the micro watershed level, yet good hydrological management necessitates effort at the macro watershed level. It also helps in recharging groundwater which is depleting in Delhi at alarming rate.

Strain induced changes in performance of strained-Si/strained-Si1-y Ge y /relaxed-Si1-x Ge x MOSFETs and circuits for digital applications

Growing a silicon (Si) layer on top of stacked Si-germanium (Ge) compressive layer can introduce a tensile strain on the former, resulting in superior device characteristics. Such a structure can be used for high performance complementary metal-oxide-semiconductor (CMOS) circuits. Down scaling metal-oxide-semiconductor field-effect transistors (MOSFETs) into the deep submicron/nanometer regime forces the source (S) and drain (D) series resistance to become comparable with the channel resistance and thus it cannot be neglected. Owing to the persisting technological importance of strained Si devices, in this work, we propose a multi-iterative technique for evaluating the performance of strained-Si/strained-Si1-y Ge y /relaxed-Si1-x Ge x MOSFETs and its related circuits in the presence of S/D series resistance, leading to the development of a simulator that can faithfully plot the performance of the device and related digital circuits. The impact of strain on device/circuit performance is also investigated with emphasis on metal gate and high-k dielectric materials.

A New Type of Self-Aligned Technology for RF and Microwave Graphene Field-Effect Transistors

A new type of fully self-aligned technology for graphene field-effect transistors was presented, in which a PVD SiO2 layer was taken as mask for the deposition of self-aligned source, drain and gate contacts. In this key process, the dielectric edge-sides exposure phenomenon during metal thermal evaporation was exploited. In the prepared self-aligned GFETs, both parasitic capacitance of the gate overlapped source and drain areas and series resistance of the spacing areas between gate and source and drain contacts were eliminated. The DC characterization and on-chip microwave measurement of the fabricated GFETs with channel length of 1give a maximum transconductanceof 2.32,field-effect mobilities of electrons and holes of 6924and 7035, and intrinsic cutoff frequencyof 0.5GHz, respectively, showing a significant improvement of both DC and RF performance.

The effect of drain blocking on the dissolved organic carbon (DOC) budget of an upland peat catchment in the UK

Summary Extensive drainage of UK peatlands has been associated with dehydration of the peat, an increase in water colour and a loss of carbon storage. It has been considered that the blocking of these drainage channels represents a means of peat restoration and a way of reducing dissolved organic carbon (DOC) losses to surface waters. This study aimed to assess the effectiveness of drain blocking at both an individual drain scale and at a larger catchment scale (up to 1 km 2 ). A series of blocked and unblocked catchments were studied in Upper Teesdale, Northern England. A detailed sampling programme was undertaken in which a series of drains were studied in the 12 months prior to and post blocking in comparison to a set of drains that were left unblocked and a catchment of similar scale where there had never been drainage. These stream networks were monitored for both their DOC concentration and export (flux per unit area). The results show that: (i) For DOC concentrations, a significant decline due to drain-blocking was only found at the first order scale when considered relative to control and relative to a pre-blocking period; (ii) drain blocking significantly reduces DOC export by reducing water yield in the drain and that the size of this DOC export reduction declines with increasing scale from 9.2% on zero order drains to 2.2% on first order drains; (iii) a linear relationship exists between DOC export and water yield at the zero order scale but this relationship becomes more complex at the first order scale as the relationship takes on the characteristics of a mixing model reflecting the effect of changing water sources with scale and providing evidence of the existence of flow bypassing drain blocks. The results suggest that effects of drain blocking decrease with increasing scale and that the presence of bypass flow around zero order blockages may limit the success of drain blocking as a method of reducing DOC loss as scale increases.

Analytical Solution for Drainflows from Bilevel Multiple-Drain Subsurface Drainage Systems

AbstractWaterlogging and soil salinisation is widespread in the semiarid, irrigated areas of the world. Subsurface drainage is a useful tool in reducing these effects on crops; however, there has been negative downstream effects of drainage in the salt loads discharged to rivers, lakes, and wetlands. Thus, subsurface drainage in semiarid, irrigated areas needs to balance the demands of providing adequate waterlogging and salinity control while minimizing salt loads. Bilevel drainage, in which shallow drains are placed between deeper drains, is a potential method to meet this required balance. This paper describes the development of an analytical solution to this design approach. A previous potential theory was extended to incorporate multiple series of shallow drains placed between two deep drains. The analytical solution was then applied using the Mathematica software to provide useful information on flow rates and flow lines with varying configurations of deep and shallow drains. The theory was then use...

Implementing low-cost landslide risk reduction: a pilot study in unplanned housing areas of the Caribbean

Landslides pose a serious physical and environmental threat to vulnerable communities living in areas of unplanned housing on steep slopes in the Caribbean. Some of these communities have, in the past, had to be relocated, at costs of millions of dollars, because of major slides triggered by tropical storm rainfall. Even so, evidence shows that: (1) risk reduction is a marginal activity; (2) there has been minimal uptake of hazard maps and vulnerability assessments and (3) there is little on-the-ground delivery of construction for risk reduction. This article directly addresses these issues by developing a low-cost approach to the identification of the potential pore pressure changes that trigger such slides we seek to address these three commentaries directly. A complex 45–60° slope site in St Lucia, West Indies was selected as a pilot for a modelling approach that uses numerical models (FLAC and CHASM) to verify the need for surface water management to effectively reduce landslide risk. Following the model confirmation, a series of drains were designed and constructed at the site. Post-construction evidence indicates the methodology to be sound, in that the site was stable in subsequent 1-in-1 to 1-in-4 year rainfall events. A critical feature of the approach is that it is community-based from data acquisition through to community members participating in construction.

An improved drain-current-conductance method with substrate back-biasing

A previously developed drain-current-conductance method (DCCM) is extended to investigate the effect of back-bias on LATID NMOSFETs. For the same effective gate overdrive, the extracted drain and source series resistances increase as the back-bias is increased. Two-dimensional device simulation showed that the increased back-bias results in reduced current contour values at the drain/source regions as a result of the increase in the series resistances.

A new approach to extract the threshold voltage of MOSFETs

A new method is presented to extract the threshold voltage of MOSFETs. It is developed based on an integral function which is insensitive to the drain and source series resistances of the MOSFETs. The method is tested in the environments of circuit simulator (SPICE), device simulation (MEDICI), and measurements.

The concept of in-situ vapor stripping for removing VOCs from groundwater

An in-situ remediation procedure is proposed to remove Volatile Organic Compounds (VOCs) dissolved in groundwater. This is accomplished by injecton of air into a well, using a combined technique of air-lift pumping with a form of vapor stripping. When air is injected into a well, it causes water to be lifted and forces groundwater flow towards the well, creating a recirculating cleanup zone. During this process, VOCs are transferred from the contaminated water to the rising air bubbles inside the well. The air bubbles are separated from the liquid near the top of the well, and the VOC vapor is collected and treated. In this system, water is not permitted to be lifted to the ground surface. Rather, the water is diverted into the unsaturated zone through a series of drains that are installed beneath the root-zone. The water then, free of a portion of VOCs, infiltrates back to the water table. As water continues to circulate, the VOC concentrations are gradually reduced.

Determination of the gate-voltage dependent series resistance and channel length in sub micron LDD-MOSFETs

In short channel MOSFETs the effects of series resistance become increasingly important. In this paper the limitations of two existing series resistance measurement methods [1,2] will be discussed. Because of their limitations a new measurement method will be presented for the determination of the gate voltage dependent series resistance. In addition a very useful numerical process and device simulation method to estimate the source (drain) series resistance under several bias conditions will be discussed.

Corrections to "Source, drain, and gate series resistances and electron saturation velocity in ion-implanted GaAs FET's"

Corrections to "Source, drain, and gate series resistances and electron saturation velocity in ion-implanted GaAs FET's"

Carrier mobility determination in short-channel MOS devices

The measurement of the effective carrier mobility in the inversion layer becomes complicated when the device dimentions are reduced. A method is described to determine the field effect mobility, the decrease of the mobility under the influence of normal electrical field, described by the surface scattering factor, and the drain and source series resistances. The degradation in the properties of the Si−SiO 2 region which is manifested as a decrease in the low field mobility of the inversion layer carriers is considered.

Uplift Pressure in Crack Below Dam

A specific analytical solution for flow through a horizontal crack of finite length drained by a series of vertical drains is presented. The solution is used to derive diagrams of uplift pressure on the base of a dam and to demonstrate the influence of drains on the distribution and magnitude of uplift forces. Our solution shows that there should be an almost linear drop in hydraulic head from the entrance to the crack at the heel of the dam to the line of drains, followed by a slight rise in head to the end of the crack. This is consistent with a previously suggested solution for porous media. The results show that drain holes are effective in substantially reducing uplift pressures in a crack and have the greatest influence when located between approximately one half and one fifth of the length of the crack from its upstream end.

Inflow of water into a discontinuous drainage system consisting of a linear series of horizontal nonideal tubular and ribbon drains

Inflow of water into a discontinuous drainage system consisting of a linear series of horizontal nonideal tubular and ribbon drains