Soil salinity-sodicity and land use suitability in the Fordwah Eastern Sadiqia (South) irrigated area

Soil salinity / Sodic soils / Soil classification / Soil surveys / Soil analysis / Groundwater development / Water table / Water quality / Land use / Irrigation canals / Farmer participation / Surface drainage / Subsurface drainage / Soil reclamation / Waterlogging / Pakistan / Fordwah Eastern Sadiqia / Bahawalnagar District

Cell wall microstructure, pore size distribution and absolute density of hemp shiv

This paper, for the first time, fully characterizes the intrinsic physical parameters of hemp shiv including cell wall microstructure, pore size distribution and absolute density. Scanning electron microscopy revealed microstructural features similar to hardwoods. Confocal microscopy revealed three major layers in the cell wall: middle lamella, primary cell wall and secondary cell wall. Computed tomography improved the visualization of pore shape and pore connectivity in three dimensions. Mercury intrusion porosimetry (MIP) showed that the average accessible porosity was 76.67 ± 2.03% and pore size classes could be distinguished into micropores (3–10 nm) and macropores (0.1–1 µm and 20–80 µm). The absolute density was evaluated by helium pycnometry, MIP and Archimedes’ methods. The results show that these methods can lead to misinterpretation of absolute density. The MIP method showed a realistic absolute density (1.45 g cm−3) consistent with the density of the known constituents, including lignin, cellulose and hemi-cellulose. However, helium pycnometry and Archimedes’ methods gave falsely low values owing to 10% of the volume being inaccessible pores, which require sample pretreatment in order to be filled by liquid or gas. This indicates that the determination of the cell wall density is strongly dependent on sample geometry and preparation

The whistler nozzle phenomenon

The whistler nozzle is a simple device which can induce jet self-excitations of controllable amplitudes and frequencies and appears highly promising for many applications involving turbulent transport, combustion and aerodynamic noise. The characteristics of this curious phenomenon are documented for different values of the controlling parameters and attempts to explain the phenomenon. It is shown that the whistler excitation results from the coupling of two independent resonance mechanisms: shear-layer tone resulting from the impingement of the pipe-exit shear layer on the collar lip, and organ-pipe resonance of the pipe-nozzle. The crucial role of the shear-layer tone in driving the organ-pipe resonance is proven by reproducing the event in pipe-ring and pipe-hole configurations in the absence of the collar. It is also shown that this phenomenon is the strongest when the self-excitation frequency matches the preferred mode of the jet

The quarter-point quadratic isoparametric element as a singular element for crack problems

The quadratic isoparametric elements which embody the inverse square root singularity are used for calculating the stress intensity factors at tips of cracks. The strain singularity at a point or an edge is obtained in a simple manner by placing the mid-side nodes at quarter points in the vicinity of the crack tip or an edge. These elements are implemented in NASTRAN as dummy elements. The method eliminates the use of special crack tip elements and in addition, these elements satisfy the constant strain and rigid body modes required for convergence

Re-Scaling of Energy in the Stringy Charged Black Hole Solutions using Approximate Symmetries

This paper is devoted to study the energy problem in general relativity using approximate Lie symmetry methods for differential equations. We evaluate second-order approximate symmetries of the geodesic equations for the stringy charged black hole solutions. It is concluded that energy must be re-scaled by some factor in the second-order approximation.Comment: 18 pages, accepted for publication in Canadian J. Physic

Participatory Irrigation Management and its Financial Viability: A Case Study

Water is a key input of agriculture. In the past, the area under cultivation was small and there was less stress on farmers to grow more and more of each crop. Water was considered a free good. The situation has changed since. The increase in cropping intensity has led to a rise in the demand for irrigation water. Water is not a free good any more. The provision of irrigation water to the farmer’s fields is going to be costlier. The Government of Pakistan is spending heavily on the operation and maintenance of the irrigation system yet shortage of funds is a major reason for deferred maintenance, which threatens the operational integrity of the irrigation system [World Bank (1988) and Haq (1995)]. The shortfall in O&M funding was estimated to be more than 24 percent in 1993 [World Bank (1994)]. As poor O&M has direct effect on the productivity of agriculture, indirectly it affects the whole economy [Carruthers (1981)]. The allocation of funds for the increasing O&M costs is becoming a problem for the Government of Pakistan with every successive year. One logical answer to this problem is to increase abiana1 fees from the users of irrigation water supplies. The revenue collected through abiana may be used for O&M purposes, but it has been reported that the revenue collection is far less than the expenditures incurred. Resultantly the gap has been increasing every year [Chaudhry (1989)]. This situation demands investigation of abiana recovery and increasing O&M costs to know the real situation which in turn will help in deciding whether it is feasible to divert the financing of O&M activities towards farmer organisations (completely or partially). This paper aims at estimating the present level of operation and maintenance expenditures of the H-4-R Distributary and the present situation of the abiana collection and the extent of its leakage through different means.