Kari T. Koskinen

Effects of fluid-flow velocity and water quality on planktonic and sessile microbial growth in water hydraulic system

Water hydraulic systems use water instead of oil as a pressure medium. Microbial growth in the system may restrict the applicability this technology. The effects of fluid-flow velocity and water quality on microbial growth and biofilm formation were studied with a pilot-scale water hydraulic system. The fluid-flow velocities were 1.5-5.2 m/s and the corresponding shear stresses 9.1-84 N/m2. The fluid-flow velocity had an insignificant effect on the total bacterial numbers and the numbers of viable heterotrophic bacteria in the pressure medium. Microbial attachment occurred under high shear stresses. The fluid-flow velocity did not affect the biofilm formation in the tank. Increase in the flow velocity decreased the bacterial densities on the pipe surfaces indicating preferable biofilm formation on areas with low flow velocity. Using ultrapure water as the pressure medium decreased the total cell numbers and resulted in slower growth of bacteria in the pressure medium. Lowering the nutrient concentration retarded biofilm formation but did not affect the final cell densities. The decreasing pressure medium nutrient concentration favoured microbial attachment in the tank instead of the pipelines. In conclusion, microbial growth and biofilm formation in water hydraulic systems cannot be controlled by the fluid-flow velocity or the quality of the pressure medium.

Effect of Cavitation in Water Hydraulic Poppet Valves

Abstract In this paper, cavitation in water hydraulic poppet valves is investigated by an experimental method with a half cut test model. The situation of cavitation appearance, the effects of cavitation on the characteristics of flow rate, noise level, pressure distributions and the boundary of inception of the cavitation are investigated. Comparison between a poppet valve with sharp edged seat and another, which has a length on the seat, is made. The effects of change in the shape of the seat are discussed as well as the effect of cavitation appearance. As a result, it is revealed that the sharp edged seat valve is less influenced by the cavitation on its characteristics.

Accurate Trajectory Tracking Control of Water Hydraulic Cylinder with Non-Ideal on/off Valves

Abstract The aim of the work is to develop an on/off valve based trajectory tracking control solution without fast and/or continuous switching of valves. The pulse code modulation method is used to realise stepwise control of inflow and outflow of the actuator. Both inflow and outflow paths have five parallel-connected two-way solenoid valves, each having different flow capacity according to binary series, and a four-way on/off valve is used for changing direction of movement. Cost function based open-loop and closed-loop control solutions are developed and it is demonstrated how the cost function weights can be used to find a reasonable trade-off between tracking performance and pressure surges. Closed-loop results show accurate and reasonably smooth position tracking and simultaneous pressure level control. Achieved control performance is close to that of water hydraulic servo systems.

An implementation of a semantic, web-based virtual machine laboratory prototyping environment

Creation of virtual machine laboratories - simulated planning and learning environments demonstrating function and structure of working machines - often involve a lot of manual labor. A notable source of the labor is the programming required due to changes in structural and functional models of a system. As a result, rapid prototyping of a virtual machine laboratory becomes difficult, if not impossible. We argue that by using a combination of semantic modeling and prototyping with a web-based system, more rapid development of virtual machine laboratories can be achieved. In this paper, we present the design and implementation of a semantic, web-based virtual machine laboratory prototyping environment. Application of the environment to a case example is also described and discussed.

Steady State and Dynamic Characteristics of Water Hydraulic Proportional Ceramic Spool Valve

Abstract Water hydraulics is both old and new technology area. The first fluid power applications were using water as pressure medium already in 18th-century, but the modern water hydraulics has been rapidly growing just recently in 1980s and 1990s. The main reasons for the comeback are environmental and safety aspects. Water hydraulics offers a significant alternative to establish motion control systems in environments, where possible oil leakage can cause serious problems. One of the major tasks to solve in modern water hydraulics is to achieve more accurate control systems than today`s technology provides. The present water hydraulic control valves are not yet at the same technology level as that of oil hydraulics. This means that a lot of effort has to be put to develop better and more accurate valve constructions and on the other hand more intelligent control methods has to be developed to achieve reasonable valve characteristics. This paper concentrates on a study of water hydraulic proportional valves, which are still very new developments in water hydraulics. The steady state and dynamic charateristics of water hydraulic proportional ceramic spool valve is studied both by computer simulation and laboratory tests. Some constructional improvements for the valves are studied and also different control methods are discussed and proposed.

Collaborative Systems and Environments for Future Working Life: Towards the Integration of Workers, Systems and Manufacturing Environments

While the industrial sector in Europe was previously strongly based on mass production technology, it is now moving towards highly customised products and thus to lot-size-one production. The change in production paradigm is strengthened by the emerging technologies. In small- and medium-sized enterprises (SMEs), this means, for example, the increased use of modern digital manufacturing tools, new additive manufacturing processes and novel engineering intelligence solutions. As a direct result, workers need to develop new skills and competences to effective work. From an educational perspective, it is especially critical that people with few prior successful experiences with fully applying the key information-processing skills need to obtain adequate comprehension to guide them in structural changes in their future working lives. In this chapter, we will discuss the critical points of adults’ skills based on the PIAAC large-scale assessment results and illustrate novel educational approaches to meet the emerging needs on the digitalisation of work. Based on these critical points, we will illuminate two learning approaches that can guide educational efforts in designing ‘future’ learning at manufacturing sector. Our first approach is a pedagogical evidence-based physical and virtual learning environment that is based on learning in a reality-conform production environment. In our second approach, we will illustrate a simulation-based learning environment that is designed to increase the understanding of complex machine systems.

Engineering intelligence - Product-service concepts and requirements in industry

European manufacturing and construction sector is wrestling with the fundamental and rapid changes in their business environment. Business environment is becoming more dynamic and distributed, thus old standardization and mass-customization methods can no longer support the companies. In order to survive the companies must be able to offer fully customized product-service concepts instead of technical solutions. This causes challenges relating to efficiency of collaboration, utilization of information flows, agility and interoperability of technical solutions and operation culture. The products, processes and services need to be designed “for humans by humans”. The competence development methods and enhanced learning have to be comprehensively taken into account. This paper summarizes the challenges among industry and provides a new approach Engineering Intelligence Ecosystem (EIE) that addresses aforementioned challenges of complex engineering systems.

Sliding mode tracking control of a low-pressure water hydraulic cylinder under non-linear friction:

Abstract This paper deals with a robust motion control of a low-pressure water hydraulic cylinder under non-linear friction. In order to ensure good tracking performance as well as to guarantee robustness, the sliding mode tracking control is utilized in combination with a non-linear friction compensator. Application of the scheme to a low-pressure water hydraulic cylinder position control has led to a significant reduction in tracking error when compared with the perfect tracking control scheme.

Early stage design of a spherical underwater robotic vehicle

This paper presents a high performance autonomous underwater robot under development for inspection of flooded mines up to 500 meters depth. Underwater robots have multiple advanced subsystems and mechanisms. Initial structure design of subsystems and their functions are demonstrated here briefly. In addition, Hydrodynamic coefficients that contribute to robot equation of motion are addressed. The advantage of utilizing spherical design is verified by applying simplification to determine the main coefficient of motion theoretically.

Data Analysis Process of working Hydraulics of small Mobile Machine

Abstract Changing work sequences and the operational environment makes the condition monitoring of mobile work machines more challenging compared with industrial systems. This sets special demands in regard to the analysis of the data measured from the machine during operation. A forklift, reach stacker, is used here as a research platform to study the operation of the data analysis process of working hydraulics of small mobile machine. The focus in the data analysis process is on feature extraction and classification parts. Discrete wavelet analysis is used to extract features which are then classified using the Self-Organizing Map (SOM). In addition, the sensitivity of data analysis process is studied. A simulation model of the lifting movement of the forklift is made to study the effects of changes in the fault levels of the performance of the data analysis methods.