Effects of species and moisture content on penetration of liquid in laser incised lumber by the passive impregnation method

Penetration of liquid by passive impregnation method for Douglas-fir (Pseudotsuga menziesii Franco), sugi (Cryptomeria japonica D. Don) and Japanese larch (Larix leptolepis Gordon) was studied. Effects of initial moisture content of sugi (16, 43 and 70% moisture content) on liquid penetration were also studied. Dried Douglas-fir (mc=14%) and sugi (mc=16%), and green Japanese larch (mc=45%) and sugi (mc=70%) were treated by passive impregnation method for penetration analysis. It was observed that dried sugi had the highest level of liquid penetration both in length (170 mm) and width (8 mm) for all measured sections followed by green sugi, green Japanese larch and dried Douglas-fir. In case of different initial moisture content, the highest absorption (624 kg/m³) and penetration (maximum 87 and 96% at cross and longitudinal surfaces, respectively) was observed for sugi having the lowest initial moisture content under the same passive impregnation conditions. Absorption and penetration decreased with the increase of initial moisture content for sugi. These results could help in designing incising pattern and density, as well as solving the problems related to high initial moisture content of wood for passive impregnation.     

A dimensioning and tolerancing methodology for concurrent engineering applications II: comprehensive solution strategy

Dimensioning and tolerancing (D&T) is a multidisciplinary problem which requires the fulfillment of a large number of dimensional requirements. However, almost all of the currently available D&T tools are only intended for use by the designer. In addition, they typically provide solutions for the requirements one at time. This paper presents a methodology for determining the dimensional specifications of the component parts and sub-assemblies of a product by satisfying all of its requirements. The comprehensive solution strategy presented here includes: a strategy for separating D&T problems into groups, the determination of an optimum solution order for coupled functional equations, a generic tolerance allocation strategy, and strategies for solving different types of D&T problems. A number of commonly used cost minimization strategies, such as the use of standard parts, preferred sizes, preferred fits, and preferred tolerances, have also been incorporated into the proposed methodology. The methodology is interactive and intended for use in a concurrent engineering environment by members of a product development team.     

ROUTE TO CHAOS IN CHEMICALLY ENHANCED THERMAL CONVECTION IN POROUS MEDIA

Exothermic chemical reactions can influence natural convection effects in a porous medium. Such phenomena may occur in tubular reactors, oxidation of solid materials in large containers, chemical vapor deposition systems, liquid explosives, and others. Experimental evidence indicates that the influence of natural convection in many chemically reacting systems cannot be neglected.

In the present work, transient effects of a two-dimensional convection generated and sustained by an exothermic chemical reaction and a constant boundary wall temperature are studied. The Darcy-Boussinesq equations are used to describe fluid flow through porous media with a zero-order chemical reaction. A recently developed method is used to compute the singular points (such as limit and symmetry breaking bifurcation points) precisely as a function of Rayleigh (Ra) and Frank-Kamenetskii (Fk) numbers. Fold curves are drawn as a function of Ra, and Fk. Flow behavior is governed by two natural parameters, namely, Ra and Fk. Multiple stationary solutions arise over an intermediate range of Ra. The solution structure, i.e., the interconnections between the various branches appear quite complicated. Determination of linear stability on the these solution branches reveal that all two-dimensional, stationary solutions develop some form of instability at higher values of Ra. Transient simulations reveal the emergence of time periodic solutions at higher Ra. The nature and frequency of these periodic solutions depend on the route followed in the parameter space Fk and Ra. The various routes to chaos are identified in this parameter space.     

Nonlinear Interval Parameter Programming Combined with Cooperative Games: a Tool for Addressing Uncertainty in Water Allocation Using Water Diplomacy Framework

Water Resources Management - This paper shows the utility of a new interval cooperative game theory as an effective water diplomacy tool to resolve competing and conflicting needs of water users...     

Implications of Biofuel Policies for Water Management in India

India has developed a national biofuel policy to increase energy security, reduce greenhouse gas emissions, and stimulate rural development. In this policy, the government has set blending targets for mixing ethanol and biodiesel with gasoline and diesel, respectively. In India, ethanol is produced from irrigated sugar-cane while biodiesel is produced from jatropha, which is said to require no irrigation. This paper analyzes the possible impacts of an increase in sugar-cane and jatropha production on water management and use. It finds that India's biofuel policy is likely to place additional pressure on scarce water resources. Although the development of biofuels may be necessary, care must be taken to anticipate its likely impacts on water resources.     

Raman amplifiers for telecommunications

Raman amplifiers are being deployed in almost every new long-haul and ultralong-haul fiber-optic transmission systems, making them one of the first widely commercialized nonlinear optical devices in telecommunications. This paper reviews some of the technical reasons behind the wide-spread acceptance of Raman technology. Distributed Raman amplifiers improve the noise figure and reduce the nonlinear penalty of fiber systems, allowing for longer amplifier spans, higher bit rates, closer channel spacing, and operation near the zero-dispersion wavelength. Lumped or discrete Raman amplifiers are primarily used to increase the capacity of fiber-optic networks, opening up new wavelength windows for wavelength-division multiplexing such as the 1300 nm, 1400 nm, or short-wavelength S-band. As an example, using a cascade of S-band lumped amplifiers, a 20-channel, OC-192 system is shown that propagates over 867 km of standard, single-mode fiber. Raman amplifiers provide a simple single platform for long-haul and ultralong-haul amplifier needs and, therefore, should see a wide range of deployment in the next few years