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This comment provides a critical analysis of Van Beukering and Bouman's [World Development 29 (2001) 1717] article on global paper recycling and trade. We first question their notion that developing countries specialize in waste paper utilization and developed countries in recovery activities primarily because of different patterns of waste paper trade. An increased focus on relative waste paper availability, we argue, provides us with a better understanding of global paper recycling. We also criticize some of the implicit assumptions made in their regression analysis of waste paper utilization rates. An alternative regression model is therefore derived and estimated. In contrast to the approach used by Van Beukering and Bouman our analysis (a) is consistent with basic microeconomic theory; (b) distinguishes clearly between short- and long-run impacts; and (c) produces results that support our initial conjecture that waste paper availability is the most important determinant of waste paper use. Key words--waste paper, recycling, trade, developing countries, developed countries, utilization

The purpose of this paper is to present a state variable model for the drying section of a paper-making machine. This model is based on the mass and energy balance relationships written for steam, paper, cylindrical heater wall, and moisture. These relationships give a set of six nonlinear partial derivative equations. The form of these equations changes somewhat from one cylindrical heater to another. The solution for this model yields the operating parameters needed to achieve the desired steam temperature while obtaining good paper drying. Boundary conditions are specified by a stochastic generator, and initial conditions are obtained by solving the static model. The dynamic model is presented in [1]. In this paper, we present only the state variable model for the paper drying, as well as comparing the obtained results with dynamic model results. Solving the set of differential equations with respect to the boundary conditions, we obtain the standard form of the state representation, which represents the dynamic version of the model used for process control. In conclusion, it can be said that the consistency of the model with experimental results seems to be reasonably good and can be used for process control. Index Terms - Drying paper, linearization, state equations, steam dryer.

Historians have argued only nominal progress was made towards improving forestry practices in Ontario during the 1920s. These previous accounts have ignored, however, several remarkably progressive silvicultural programmes carried out by the province's pulp and paper companies - including that undertaken by the Abitibi Power and Paper Company, Limited - in the decade after the First World War. During this period, without any prodding from the government, Abitibi began managing its timber limits on a sustained yield basis. Although the Crown showed no interest in assisting this company in its groundbreaking project, Abitibi's work in this regard stands as a testament to the industrial forestry initiatives of the 1920s.

Kraft pulp and paper mills generate large quantities of black liquor and byproduct biomass suitable for gasification. These fuels are used today for onsite cogeneration of heat and power in boiler/steam turbine systems. Gasification technologies under development would enable these fuels to be used in gas turbines. This paper reports results of detailed full-load performance modeling of pulp-mill cogeneration systems based on gasifier/gas turbine technologies and, for comparison, on conventional steam-turbine cogeneration technologies. Pressurized, oxygen-blown black liquor gasification, the most advanced of proposed commercial black liquor gasifier designs, is considered, together with three alternative biomass gasifier designs under commercial development (high-pressure air-blown, low-pressure air-blown, and low-pressure indirectly-heated). Heavy-duty industrial gas turbines of the 70-M[W.sub.e] and 25-M[W.sub.e] class are included in the analysis. Results indicate that gasification-based cogeneration with biomass-derived fuels would transform a typical pulp mill into a significant power exporter and would also offer possibilities for net reductions in emissions of carbon dioxide relative to present practice.

The thermophysical properties of artificially aged paper samples were evaluated using the photothermal deflection technique. The technique had been proposed for the measurement of the transmittance and the reflectance values of the given paper sheet. It had also allowed the estimation of thermal diffusivity, optical absorption and the scattering coefficient values of all samples examined.

Laser-induced plasma emission spectroscopy (LIPS) has been used to study inorganic pigment and organic binder distributions in paper coatings, which are inhomogeneous and porous materials. The plasma was generated by focusing a pulsed XeCl excimer laser beam (diameter 100 [[micro]meter], irradiance 0.3 GW/[cm.sup.2]) on the sample surface at atmospheric pressure. A gated intensified CCD detector was used to record time-delayed emission spectra. Linear correlations between the LIPS signals and the coat weight and the binder content of the coatings studied were obtained. Emission line intensities from ionic and neutral magnesium atoms were used to evaluate plasma temperature corrections in determining silicon and calcium in coatings. Self-absorption of the Ca(I) 423-nm line in air was observed for the coatings containing calcium carbonate. In an argon buffer, self-absorption was not present. Pigment and binder depth profiles of the coatings were studied for several coated paper samples. All samples studied indicated binder enrichment on the top layer of the coating.

In recent years there has been a renewed interest in modeling the halftone microstructure to better control the colors produced in a halftone image. Diffusion of light within the paper has a significant effect on the halftone color; this effect is known as optical dot gain or the Yule-Neilsen effect. Because of diffusion, a photon may exit the paper from a different region of the halftone microstructure than that into which it entered the paper. To account rigorously for this effect requires knowledge of the paper's point-spread function or, equivalently, the paper's modulation transfer function (MTF). A new technique for measuring the MTF of paper - the series-expansion bar-target technique - is introduced. The method uses a bar target, but the analysis more closely resembles that of the edge-gradient technique. In the series-expansion method, bar-target image data are expanded into a Fourier series, and the paper's MTF is given by the series-expansion coefficients. It differs from the typical bar-target analysis in that the typical method plots the amplitude of the fundamental frequency component for several targets of varying frequency, whereas the series-expansion method plots the amplitude of the fundamental and its harmonics for a single target. Two possible techniques for measuring the MTF with the bar-target series-expansion method are considered. In the first, the image of the bar target is projected onto the paper, and in the second, the bar target is placed directly on the paper, in close contact.

The potential of the paper-bill spread to foresee business cycle changes dwindled in the 1980s as liquidity of commercial paper increased. The latter incited investors to consider paper as an approximate alternative for Treasury bills. Consequently, shocks to the paper and bill markets did not significantly affect the paper-bill spread but were actually incorporated by proportional yield alterations in both markets. This findings veer away from explanations that attribute the predictive decline to market contractions and to changes in paper and bill supplies unrelated to business conditions.

US paper mills are being influenced by Western Europe to change from acid paper to alkaline paper because of its many economic and environmental advantages. Alkaline paper lasts longer and is brighter than acid paper. The paper mills benefit because energy expenditures, fresh water use, machine corrosion and effluent treatments are reduced while sizing is more efficient and recycling is easier. Alkaline paper uses synthetic sizing agents and can use a broader spectrum of mineral fillers, such as calcium carbonate. However, the transition will require careful planning by paper mills.

Reliability and power quality are two of the most discussed topics in the utility industry today. Many groups have performed power quality studies with varying results. One large industrial customer in northern New York State which experienced numerous process interruptions due to power system disturbances was the focus of this study. Monitoring methods, results, inadequacies of standards, and unique mitigation techniques used to conquer their problems are discussed in this paper.

Kraft paper is used extensively in the electricity supply industry for the insulation of HV apparatus, such as transformers, capacitors and cables. Because of the fibrous nature of the paper, many layers are stacked or rolled to obtain the required electric strength. The insulation is thus a combination of cellulose and an impregnating fluid, which may be a liquid, a gas or vacuum. The dielectric properties of such a system depend on the dryness, temperature, frequency and the degree of mechanical compression. Although the effects of moisture, temperature and frequency on the dielectric properties of kraft paper have been studied, very little work has been done on the effect of compressive stress, particularly long-term effects. Results are presented of measurements, in the frequency range 50 Hz to 20 kHz, of the effects of compressive stress and temperature on the real and imaginary parts of the complex relative permittivity of a multilayer stack of dry kraft paper under vacuum. The variations of the dc resistance with compressive stress and temperature also are reported. Results are given of the variation of the dielectric properties of a stack of paper following a step change in either the temperature or the air pressure. The long-term variations are attributed to the slow diffusion of ions through the stack, particularly those held at the interfaces between layers.

The tolerance and aggression between nestmates and non-nestmates were studied in the paper wasp, Polistes dominulus, to determine whether nestmate discrimination is context-dependent. Three contexts were considered, namely dyads composed of a pair of non-nestmates, dyads composed of a pair of nestmates and triads composed of two nestmates and a non-nestmate. The findings showed that P. dominulus workers are capable of distinguishing between neighbors from non-neighbors, familiar from unfamiliar fragments and nestmates from non-nestmates.

Paper preservation is important to many areas, such as the government, libraries, universities and the pulp and paper industry, and acid-catalyzed hydrolysis has been determined to be the main factor in paper deterioration. Therefore, several methods of mass deacidification have been developed to neutralize the acid in paper. There has also been research into alkaline paper which would reduce the risk of acid-caused deterioration as well as producing paper cheaper, with less pollution and equipment erosion and reduced energy consumption.

It has become increasingly common for paper mill sludge to be reused, rather than landfilled. Some is being returned to the paper production cycle, while some is being used for other applications. In 1995, the members of the National Council of the Paper Industry for Air and Stream Improvement, which account for around 70% of the US papermaking industry, produced just under 3.9 million tons of sludge. Some 25% of this was covered by utilization schemes, with 25% being incinerated and around 50% landfilled or lagooned. Applications for paper mill sludge include land reclamation and agriculture.

Paper is made by a continuous high-speed filtration drainage of an aqueous suspension of fibers. This paper presents a new approach to the controllable simulation of paper forming, using artificial neural network methods. The model incorporates dynamics of the forming process, like turbulence, drainage speed, and preferential drainage through earlier less-dense regions and fiber properties, like propensity to clump, or 'flocculate,' fiber flexibility, and concentration of fibers in the suspension. Results for monofiber layer structures are described, showing effects of turbulence and its decay during drainage in causing clumping, or 'flocculation.' The commercial process has, as one of its main goals, the reduction to tolerable levels of the nonuniformity in mass distribution resulting from flocculation. The new model yields data corresponding to that obtainable along arbitrary scanning lines in planar stochastic fibrous structures, providing profiles, variances, histograms of local areal density, and histograms of local free-fiber lengths. These results closely resemble experimental data from commercial paper samples obtained from radiographic or optical transmission images subjected to image analysis. Index Terms - Drainage, fabric, flocculation, formation, forming, neural networks, simulation, turbulence.

Motor failures are very costly in a typical paper mill. Typical motor failure cost upwards of $20 000 per hour. Motor repair costs for the North American mills of Champion International total over $10 000 000 per year. Lost production associated with these failures can reach a staggering $1 000 000 per day. Considering these facts, Champion International embarked on a program to use intelligent motor control and protection equipment in all new installations, where applicable, and to replace outdated motor protection equipment. The combination of advanced motor protection, flexible control, and communication provided Champion with the opportunity to directly control and monitor their processes. The advanced features of the new equipment provide warning of impending problems, minimize downtime, and improve process results. This paper provides case histories where the new equipment replaced dated electromechanical protection and control equipment. In addition, we also discuss the present generation of motor protection technologies and the need for a new generation of motor protection equipment that truly provides total motor protection against all known motor failure modes. Index Terms - Case histories, failure cost, monitoring, motor, thermal protection.

Throughout virtually all mass production industries in North America, including the Canadian newsprint industry, a significant theme of restructuring involves a transition from 'Fordist' to more 'flexible' methods of production and employment. In this paper, shifts towards smaller, more flexible employment conditions are assessed from the perspective of a model of 'high-performance organizations'. In this model, employment flexibility is defined in terms of the blurring of the boundaries between management and workers and by continual investment in skill promotion in the pursuit of a polyvalent workforce. In practice, such issues are subject to labour-management bargaining, the outcomes of which are uncertain. Empirically, this paper provides a case study of bargaining over employment flexibility, specifically at the Powell River paper mill, to assess the extent to which the standards of the high-performance model are being achieved. Key words: high performance, neo-Taylorism, bargaining, Powell River