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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.

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.

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.

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.

A theoretical model for simulation of conventional steam-heated cylinder dryers is developed by considering the heat and mass transfer in a porous sheet during drying. Expressions for sheet shrinkage as a function of mass of water removed and for reductions in sheet porosity are derived for inclusion in the model. The interface thermal contact conductance of moist paper handsheet/metal interfaces has been experimentally investigated. A resulting empirical correlation, representing the thermal contact conductance between the cast iron dryer surface and paper web, is incorporated into the drying simulation model to reflect reductions in heat input to the sheet during drying. Finite difference techniques are used to obtain the numerical solutions. Average sheet moisture content and temperature along the length of the dryer section as well as average evaporation rates per cylinder are predicted by the model. Consideration of the internal dynamics of the drying process allows profiles of sheet moisture content, temperature, liquid flux, and vapor flux through the sheet thickness to be developed throughout the dryer section. Drying results are consistent with actual production cases. The model can be used to design dryer sections, study changes in operating conditions or in layout of a multi-cylinder dryer, or simulate the application of enhanced drying devices to a conventional drying section. The effect of the drum/paper contact conductance on drying rates and resultant dryer section requirements is provided as an example application of the model.

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

The Canadian government and the country's pulp and paper industry face the tough challenge of identifying and controlling the unknown mill effluent constituents which cause environmental harm. To date, the government has regulated effluent testing as well as dioxins and furans. It has, however, declined to regulate adsorbable organic halogens, move that proved to be economically justified by subsequent research. Meanwhile, Environment Canada is promoting effluent-free pulp and paper mills via strategic alliances.

A novel method was developed for the analysis of nonylphenol polyethoxy carboxylate metabolites (NPEC) in municipal sewage treatment plants. The method utilizes 4-bromophenylacetic acid as a surrogate standard for the NPEC metabolites of nonylphenol polyethoxylate surfactants. The method was utilized to recover 106-138% of NPEC from composite paper mill effluents. The levels of NPEC from water samples taken from fifteen paper mills were below the lethal dose that leads to fish kill.

This study investigates the geotechnical properties of seven paper mill sludges. Paper mill sludges have a high water content and a high degree of compressibility and behave like a highly organic soil. Consolidation tests reveal a large reduction in void ratio and high strain values that are expected due to the high compressibility. Triaxial shear-strength tests conducted on remolded and undisturbed samples showed variations in the strength parameters resulting from the differences in sludge composition (i.e., water content and organic content). Laboratory permeability tests conducted on in-situ specimens either met the regulatory requirement for the permeability of a landfill cover or were very close. With time, consolidation and dewatering of the paper sludge improved the permeability of cover. Freezing and thawing cycles increased the sludge permeability about one to two orders of magnitude. Maximum permeability changes occurred within 10 freeze and thaw cycles.

A small cross-sectional study of upper extremity disorders was conducted in two departments of a pulp and paper mill. The objective of the study was to determine the prevalence of upper extremity disorders and identify any associated work place risk factors in long cycle jobs with multiple tasks of varying duration. Physical exams and health status interviews were conducted on 23 employees (77%) in the paper machine department and on 17 employees (59%) of the power and recovery department. All participants completed questionnaires on physical and psychosocial job characteristics. There was a statistically significant difference in hand and wrist disorders between the two departments at the p < 0.05 level (34.8% in the power and recovery department, and 5.9% in the paper machine area). Multiple logistic regression models showed a significant relationship between the use of a steel lance and shoulder disorders. Elbow arthritis was also associated with lance usage. There was evidence that the job analysis was not able to fully describe the risk factors present in the paper machine department. Biomechanical exposures existing prior to the time of the study may not have been adequately characterized. An important aspect of this study is that the jobs studied were not typical repetitive jobs that are commonly studied. Keywords: carpal tunnel syndrome, tendinitis, cumulative trauma disorder, pulp and paper, process industry

The pyrolysis kinetics of cellulosic uncoated printing and writing paper, which is one of the principal materials contributing to the municipal solid waste (MSW) of Taiwan, was investigated with a thermal gravimetric analysis (TGA) reaction system. The experiments were carried out in a nitrogen environment in the 450-850 K temperature range at various constant heating rates of 1, 2, and 5 K/min. The results indicated that there were two principal reactions in TGA curves as distinguished by the two significant and distinct mass changes over the experimental conditions. The pyrolysis of uncoated printing and writing paper can be adequately described by a two-reaction model. The corresponding activation energies, preexponential factors, and reaction orders were determined. The experimental results were satisfactorily fitted by the proposed chemical reaction model.

Oil impregnated paper or polymer film is the main insulating system for many kinds of power apparatus. The oil impregnated materials, especially oil impregnated kraft paper, include a significant amount of water, and this water disturbs the insulating performance of the devices. The amount of water in the materials usually is represented by the difference in weight between the normal material and the same material after drying. However it is difficult to measure the absolute value of the water content and to determine the state in which the water exists in the materials. In this study, we examined the IR spectra of water in oil impregnated kraft paper, because the IR spectrum of the water indicates not only the amount of water but also its state. It was found that most of the water behaves as liquid water, and some as hydrogen bonded water, interacting with the paper fiber. The dc conductivity of the kraft paper depends only on the amount and state of the water associated with it whether or not the paper is impregnated with the oil.

Paper mill black liquor and effluent samples were analyzed using in vitro recombinant receptor/reporter gene assays to determine the presence of estrogenic, dioxin-like and antiestrogenic activities. The results conclusively showed that black liquor and paper mill effluents contain estrogen- and dioxin-like ligands. However, more research is needed to identify the particular agents responsible for the adverse health effects observed in fish exposed to paper mill effluents.

A review of literature on the chemical analysis of pulp and paper published duringthe period Oct. 1992-Oct. 1994 is presented. Several topics such as lignin chemistry are avoided since only articles with direct bearing on industry are considered. However, residual lignin in pulp and paper matrices is covered since it isalso a significant factor in pulp and papermaking processes.

Higher environmental standards may improve the efficiency and competitiveness of Australia's paper industry. Although neo-classical theory posits that polluting industries will relocate to countries with relaxed regulations, an alternative theory predicts that firms will adopt proactive policies, becoming more sensitive to costs, market changes and demand, and encourage the development of new technologies.

Maimie Pinzer's 'Papers' elaborate the study and teaching of realism in literature. Pinzer uses an epistolary style to indicate the relationship between the writer and the reader. Students are critical about the vicissitudes of the narrator's voice in 'The Maimie Papers.' Students feel that as a writer Pinzer too cannot practice realism; literature is imaginative.

The Ming dynasty (1368-1644) abandoned the paper money system established by the Sung dynasty (960-1279) due to inflation problems caused by over-issuance. It was driven to do so by competition from metallic currencies which raised 'interest elasticity of paper money demand.' This is proven using the Cagan adaptive expectations model and the money-in-utility model. Likewise, the Southern Sung government's dependence on a leaning-with-the-wind feedback approach to prevent self-generating inflation is discussed.

A method for time-resolved recording of light scattering in thin, highly scattering media is described. Subpicosecond pulses from a high-power Ti:sapphire laser are used, and single-shot recordings of the scattered light are made with a fast streak camera. The method is applied to the study of light scattering in paper, and a 1-ps resolution is demonstrated. The dependence of the light scattering on the basis of weight and density of the paper has been studied. A white-light continuum generated from the high-power pulses by the use of self phase modulation in water is used to study the wavelength dependence of the scattering process. A model for the propagation of light in paper has been developed and used in Monte Carlo simulations. The experimental results are used for testing this model, and absorption and scattering parameters are determined from that comparison. Key words: Paper, light propagation, light scattering, time-resolved spectroscopy, white-light continuum, streak camera, Monte Carlo simulations.

The cutting and skiving stock problem (CSSP) as encountered in the paper industry is examined. CSSP is considered one of the most interesting generalizations of the uni-dimensional cutting stock problem. The MAJIQTRIM commercial software package is used to solve the problem using heuristic and linear techniques. The software has proven to be superior to manually generated solutions in terms of quality and performance.

Chlorinated dehydroabietic acids (DhA) result when wood pulp are bleached with chlorine. These compounds are then passed out as pulp and paper mill effluents but are very harmful to fishes. Twelve types of bacteria have been identified that could biologically degrade chlorinated DhAs. The twelve strains belong to the Proteobacteria, Sphingomonas and the Ralstonia classes.

An approach founded on the usage of physical production data as a yardstick of activity progress for the manufacturing industry is used in the study of cross-country, cross-time comparison of energy efficiency developments in the industry. The method, applied to pulp and paper industries, enabled the monitoring of energy efficiency developments, disjointly, for fuel and electricity consumption. Moreover, the method allowed the creation of physical energy efficiency comparisons between nations without requiring information at the process level.

There are several determinants of investment rivalry. These determinants form the basis for firms' decisions regarding the abandonment of previously announced capacity expansions within the North American pulp and paper industry. The determinants include the investor's initial confidence, the extent of committed resources and the announcement of fresh news. The announcement of unanticipated projects by rival firms also increases the probability of investment abandonment.