Search

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.

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.

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.

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.

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

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

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.

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.

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.

The Canadian Pulp and Paper Association estimates a 25% annual increase in the domestic demand for recyclable papers, and many Canadian mills have upgraded recycling technology to process and decontaminate a higher range of paper fibers to satiate the market demand. The improved domestic economy and new global markets have caused a major increase in paper costs, and people in Ontario, Canada are adopting innovative recycling programs to stabilize the market and to protect forests.

We present the first evidence that initial ratings of commercial paper influence common stock returns. Highly-rated industrial issues of commercial paper, unaccompanied by bank letters of credit, are associated with significantly positive abnormal returns; lower-rated issues are not. The stock price effects of changes in commercial paper ratings also demonstrate the relevance of ratings to the financing of firms. Rating downgrades, especially those that imply an exit from the commercial paper market, produce significantly negative abnormal returns; upgrades have no effects. Initial commercial paper ratings and subsequent reratings appear to help investors sort firms by their future prospects. (Reprinted by permission of the publisher.)

A model is presented which predicts the path along which ordinary machine-made paper will tear. Based on the idea of minimum work being done as the paper tears, this model leads to curve-generating equations which are solved numerically via a simple BASIC program. A key feature making this a pedagogically attractive activity is that immediate experimental feedback is possible by printing out the theoretical curves and comparing them to the actual tearing curves produced when the printouts are torn. Typical results obtained when this is done are included.

We investigated the effects of proximity of containers on pounds of office paper recycled and not recycled by 25 employees. During a memo and central container condition, one container for recyclable paper was provided; in a memo and local container condition, desktop recycling bins, announced by memo, were successively introduced across administrative, office, and instructional settings using a multiple baseline design. Only 28% of paper was recycled in the central container condition, but when recycling containers were placed in close proximity to participants, 85% to 94% of all recyclable paper was recycled. Follow-up assessments, conducted 1, 2, 3, and 7 months after all settings received local recycling containers, showed that 84% to 98% of paper was recycled. Providing desktop recycling containers was a cost-effective procedure with long-term maintenance and program survival.

Diamond (1991) argues that a firm's reputation determines whether it borrows directly or through an intermediary. We test the Diamond model by examining the quantity response of commercial paper issues by bank holding companies to a rating downgrade. From 1986 to 1991, cumulative abnormal declines averaged 6.69 percent in the first two weeks after the downgrade and 11.05 percent in subsequent 12 weeks. In contrast to commercial paper issued by bank holding companies, large CDs issued by affiliated banks did not change significantly in the period around a downgrade, suggesting that deposit insurance may have removed market discipline from the CD market. (Reprinted by permission of the publisher.)

This paper gives a broad overview of the changing pattern and nature of trade between the years 1960 and 1985, as European Community (EC) pulp and paper producers have responded to increasing global competition. Specialisation of production for member states was identified in the European trade patterns. Specialisation occurred as a result of industrial restructuring within each member state, rather than for the EC as a whole. There is no common industrial policy in the Treaty of Rome. Explanation for the nature of trade, for the member states, was provided by Porter's (1990) theory of competitive advantage. Innovative responses by firms to maintain their competitive advantage in a dynamic economy, rather than neo-classical free market principles, are emphasised in Porter's theoretical framework.

Business ownership and employee education affect productivity in China's paper industry. Business enterprises owned by provinces were found to produce about 23% less than municipality-owned and collectively-owned ones. This implies that workers become more efficient when they perceive profits to redound to their own benefit. It was also discovered that the employment of more educated workers has a very high social rate of return.

A utility capacity increase from 50 to 100 MVA was implemented in a large Kraft paper mill. All existing plant 15-kV switchgear and controls were replaced and a new tie line constructed during a nine-month period prior to the utility increase. Electrical and process control rooms were built to house new switchgear and computer control equipment. All installation work was done during outages scheduled for other plant objectives. New switchgear installed consists of 42 cells of 1000-MVA class equipment. The control system includes operator workstations, supervisory PLC, and remote I/O racks. Breaker control, metering, and loadshedding functions are performed by the control system.

Thomas Jefferson had a strong policy opposing bank notes and supporting paper money issued by the government. He considered bank notes as destabilizing to the economy. He thought that paper money would obviate a class of creditors who relied upon taxpayers. His support of government currency finance went against prevailing views, yet it was well informed by economic theory. He demonstrated a foresight on monetary policy which illustrates that his genius extended to economics.

Paper and paperboard make up 37.5% of the 196 million tons of municipal solid waste produced annually in the US. Luckily, there has been an increase in the volume of recycled paper. The American Paper Institute calculates that about 29 million tons of paper were retrieved for recycling in 1990. These wastepaper types include old newspaper, old corrugated cardboard, old telephone directories, office paper and even third class mail. These are recycled into newsprint, construction paper, printing and writing paper, tissue, feedstock, animal bedding and molded paper products.

Richard Allen invented a paper wheel in 1896 and this was used by George Pullman in the manufacture of passenger cars. Allen's paper wheel consisted of a compressed laminated paper core and an iron hub. Pullman Palace Car Company used Allen's wheel in their luxury dining and sleeping cars, as it helped to reduce sound and vibrations from the rails. However, paper wheel's popularity was short-lived as it was unable to support the heavier cars that were introduced in the early 20th century. Allen's wheel represents the spirit of the 19th century when advances in papermaking technology led to new innovations which were readily adopted by manufacturers' in their quest for higher profits.

Not all mixed paper wastes are recyclable. However, North Carolina's goals in recycling require the development of landfilling alternatives. Several options were undertaken by different groups. Mixed paper composted with sludge still requires testing applications, market development and written guidelines about the process, but full scale composting is already possible. Mixed paper was also composted with mixed organics. Temperature maintenance was found to be crucial to the process. Composting mixed paper with yard waste posed problems regarding operational details which need to be addressed.

The subject of energy-efficient lighting and lighting practices for the pulp and paper industry offers an opportunity to discuss energy-efficient lighting technologies, commencing with new current lighting products, the advantages and disadvantages of these new lighting products, coping with the disadvantages, their performance and design, and ways to apply these new products in an effective retrofit or in new construction applications. We will also review current recommended lighting practices for indoor and outdoor applications, and we will establish guidelines for improved techniques and economics with recommended illuminance values as applied to new projects or in the modernization of existing pulp and paper facilities.