Method for simulating processes of processing inhomogeneous data in buffer drives of routers

The article proposes a method for modeling the processing of heterogeneous data in the buffer storage of routers. In contrast to the existing approaches, in the developed method, in the analytical description of the processes of functioning of buffer storage devices of routers under the influence of heterogeneous traffic of subscribers of a special-purpose communication network, the apparatus of the theory of cellular automata was used, which made it possible to take into account the probability of timely processing of data of all used priority levels of communication directions.As a result of the experiment carried out on the basis of a real special communication network, it was found that the developed method of modeling the processes of processing inhomogeneous data of buffer storage devices of routers makes it possible to increase the accuracy of determining the probability of timely delivery of priority information to subscribers of a special purpose communication network, in comparison with the existing standardized methods.

Influence of storage on the physical and chemical properties of Scots pine bark

Bark is currently used mainly to produce energy, but the extraction of valuable compounds before combustion offers an interesting cascading use for debarking biomass. Buffer storage is an inevitable part of bark biomass logistics, but substantial dry matter and extractive losses can degrade the properties and reduce the economic value of the raw material during storage. In this study, moisture and ash content, calorific value, and extractives content and composition of Scots pine (Pinus sylvestris) sawmill bark were determined over 2 months of buffer storage, and the change in energy content during storage was calculated. The results showed that the energy content (MWh m−3) of the bark increased 3% during storage, while at the same time the moisture content decreased 16%. The content of acetone-soluble extractives decreased markedly, with only 56% of the original amount remaining after 8 weeks of storage. In particular, hydrophilic, phenolic extractive compounds were rapidly lost after debarking and piling of the bark. About 60% of condensed tannins (CT) and about 26% of the quantified lipophilic compounds were lost after 2 weeks of storage. The fastest rate of decrease and the most significant changes in extractives content and composition occurred within the first 2 weeks of storage. Utilization of these valuable compounds necessitates fast supply of material for further processing after debarking. The comprehensive utilization of bark requires efficiency at all levels of the supply chain to ensure that tree delivery times are kept short and loss of bark is avoided during harvest and transport.

Power station based on variable speed diesel generator and buffer storage device

The article describes the diesel generator complex which consists of two diesel generators. In order to save fuel, it is advisable to choose one diesel generator of inverter type, i.e. to switch it to a variable speed mode. The buffer storage device is used as a part of the power plant in order to ensure the required parameters of the generated electricity under peak loads, as well as when the generator is operating at the limit of rated power. There has been given the control algorithm and transient processes of the charge / discharge of the buffer storage device in a diesel generator power plant. The power plant that consists of a classic diesel generator and a variable speed diesel generator unit (valved generator) has been chosen as an object research. A block diagram of the power plant conducting is proposed, as well as a power transformer topology of a variable-speed diesel generator based on a step-down pulse-width converter. There has been presented an algorithm for controlling the connection of a buffer storage device depending on its charge and the load power value both in stand-alone mode and in parallel operation of generator sets. In the MatLab Simulink computer environment a simulation model of a power plant was developed and transient processes of load switching, as well as charge / discharge of a buffer energy storage device were studied. An electrical circuit diagram of an experimental bench of a variable-speed diesel generator set is illustrated. The results of experimental studies of dynamic modes of operation on a prototype variable speed diesel generator with a power of 3.2 kW are also presented.

Comparison of Alternative Pulpwood Inventory Strategies and Machine Systems at a Log-Yard Using Simulations

The rising throughput of log-yards imposes new constraints on existing equipment and increases the complexity of delivering an optimal and uninterrupted supply of pulpwood to pulp mills. To find ways of addressing these problems by reducing log cycle times, this work uses a discrete-event mathematics model to simulate operations at a log-yard and study the impact of three different log-yard inventory strategies and two alternative machine systems for log transportation between main log-yard and buffer storage. The yard’s existing inventory strategy of last load in and first out limits access to older logs at the main storage site. By allocating space for 89,000 m3 and 99,000 m3 of pulpwood at the buffer storage it is possible to keep the log cycle time at the main storage to a maximum of 12 and 6 months. Additionally, the use of an alternative log transportation machine system comprising a material handler with a trailer increased the work time capacity utilization relative to the yard’s current machine system of two shuttle trucks and a material handler for transporting logs between the main and buffer storage areas. Compared to the currently-used last in first out inventory strategy and purposely emptying the main storage area once or twice per year did reduce the total work time of both machine systems by 14% and 30%. Consequently, the volume delivered from the buffer to the log-yard decreased on average by 17% and 37% when emptying the main storage area once and twice per year. Even with reduced work time when emptying the main storage area, both machine systems could fulfil given work load for transporting logs from the buffer storage to the main log-yard without interrupting operations of the log-yard.