Styrmodeller och organisationsperspektiv för offentlig verksamhet och kostnadseffektivitet som är inspirerade av privat näringsverksamhet och industriell produktion har fått stort genomslag inom offentlig administrativ logik och praktik. Det gäller också styrningen av responssystemets aktörer där det framgår att mötet mellan vad som populärt kallas New Public Management och räddningstjänst omfattat av oro, konflikter och intern turbulens. Frånsett gemensamt fokus på säkerhet har de administrativa och politiska delarna av många förbund, tydligt fokus på kostnadseffektivitet i enlighet med Lean produktionsstyrning medan operativa delar av organisationen har tydligt fokus på arbetsmiljö och risker vilket omfattar andra perspektiv på vad effektivitet är.

Studiens syfte var att beskriva skillnader mellan olika effektivitetsperspektiv och dra slutsatser kring konsekvenserna av dem i organisering av räddningstjänstförbund samt att börja skissera förslag till arbetssätt och metoder för hantering av olika effektivitetsperspektiv.

Studien genomfördes med kvalitativa fallstudier av två räddningstjänstförbund: Räddningstjänst-förbundet Östra Götaland (RTÖG) och Mälardalens Brand- och Räddningsförbund (MBR). Sju personer, såväl brandmän som chefer i de två förbunden har intervjuats och ytterligare en person har avgett synpunkter på texten. interna dokument har studerats. Som komplement till intervjuerna har de intervjuade fått rangorda mål som kan kopplas till olika former av effektivitet samt av hur de förväntar sig att andra grupper rangordnar. Insamlade data har tematiserats och analyserats kvalitativt, samt positioneras utifrån en narrativ modell över olika effektivitetsperspektiv. Resultatet av den tematiska analysen har analyserats med induktiva jämförelser med och mellan HRO perspektiv och Lean och Agile produktionsstrategier.

I den tematiska analysen återfanns sex breda teman ”Yrkets omvandling”, ”Att bygga upp ett kommunalförbund inom räddningstjänst”, ”Effektivitet”, ”Organisering”, ”Trygghet och Säkerhet”, ”Utveckling framöver”. En analys av fördelningen över olika perspektiv på effektivitet visade en stark överbetoning på ett reduktionistiskt synsätt och detaljstyrning. Problem med effektivitet uttrycktes i enlighet med ett perspektiv men lösningar föreslogs som uppfyllde en annan effektivitet, vanligen föreslogs lösningar inom insatseffektivitet. Det gällde också mjuka effektivitetsvärden som delaktighet, medvetenhet, värdegemenskap. Resultatet visade att såväl cheferna som brandmännen rangordnade vad som är allra viktigast på exakt samma sätt men att förväntningar på andra var stereotypa.

Bland de perspektiv på effektivitet som stod i konflikt med varandra fanns tre huvudmotsättningar som också kunde relateras till motsättningar mellan organisationsrecepten” HRO och Lean som samexisterade i de studerade räddningstjänstförbunden och inte var kompatibla i alla sina delar. Motsättningarna gällde: Ambition om kostnadseffektivitet som ställdes mot ambition om säkerhet, behov av standardisering som ställdes mot behov av flexibilitet och ideal i form av avskalad effektivitet som ställdes mot behov av överkapacitet och redundans. Genom att kombinera Lean och HRO med ytterligare ett organisationsrecept: Agile produktion kan här motsättningarna minimeras. Det talar för vikten av att vara uppmärksam på vilka ideal och implicita värden som följer med de organisations och produktionsstrategier man använder sig av, och att kritiskt och medvetet välja produktionsekonomiska strategier som uppfyller de krav verksamheten ställer samt att vara beredd att modifiera och utveckla dem efter den egna verksamhetens behov.

These days, energy efficient mobile fluid power systems are of great interest. A mobile system containing several different cylinder drives supplied with a single load sensing pump (LS-pump) has a number of advantages as well as disadvantages. One of the main advantages is the need of only one system pump. This makes the fluid power system compact and cost-effective. A challenge is to keep the hydraulic losses at low level, especially losses at smaller loads. This paper introduces a fail-safe proportional valve element that is based on the Valvistor poppet valve. Due to the demands of flexibility the poppet valve is bi-directional. The valve has an innovative hydro-mechanical layout that makes it fail-safe, unwanted lowering loads, for example, never occur. The new valve includes simple sensors that are suitable for identification of mode switches, e g between normal, differential and regenerative modes. It is also possible to maneuver the system with maintainted velocity control in the case of sensor failure. In a less complex system the concept has benefits as well. For example in systems where fail-safe-bi-directional on/off valves are needed, then without mode sensing capabilities.

These days, energy efficient mobile fluid power systems are of great interest. A mobile system containing several different cylinder drives supplied with a single load sensing pump (LS-pump) has a number of advantages as well as disadvantages. One fo the main advantages is the need of only one system pump. This makes the fluid power system compact and cost-effective. A challenge is to keep the hydraulic losses at a low level, especially losses at smaller loads. This paper introduces a fail-safe proportional valve element that is based on the Valvistor poppet valve. Due to the demands of flexibility the poppet valve is bi-directional. The valve has an innovative hydro-mechanic layout that makes it fail-safe, unwanted lowering loads, for example, never occur. The new valve includes simple sensors that are suitable for identificaiton of mode switches, e g between normal, differential and regenerative modes. It is also possible to manoevre the system with maintained velocity control in case of sensor failure. In a less complex system the concept has benefits as well. For example in systems where fail-safe bi-directional on/off valves are needed, then without mode sensing capabilities.

Today´s mobile machines most often contain hydraulic valve controlled drives in an open loop circuit. For the purpose of saving energy, the constant pressure pumps have in the past frequently been replaced by load-sensing pumps and load-sensing valves. However, considering applications where the load is helped by the gravitational force, even these hydraulic systems often suffer from poor efficiency. In this article, a novel pump-controlled hydraulic system is studied where energy recuperation from lowering motions is posssible. The pumps are fully displaceable in both directions, working as motors when lowering loads. The amount of recuperated energy is highly dependent of the chosen control strategy, the hydromechanical properties as well as the target application. Furthermore, the article describes how valve design becomes an important feature in an attempt to reach high efficiency and machine operability.

 Vid beräkning av bränsleförbrukning och körbarhet för arbetsmaskiner såsom hjullastare är det nödvändigt att inkludera modeller av operatör och det lastade materialet. Annars utvärderas maskinen under fel förutsättningar pga att interaktionen operatör-maskin-last beror på alla dessa tre, inte bara maskinen i sig. Presentationen beskriver sätt att modellera operatör och last och jämför detta med utvärdering med fasta arbetscykler.

Mathematical modeling and the simulation of complex physical systems is a central activity in engineering. The models are the result of large investments in time and measurement equipment and therefore need to be used as efficiently as possible. If one and the same model can be run in several simulation environments and in other applications, then the model can be simulated today and tomorrow in the most appropriate environment with respect to user background, the engineering domain at hand, and more. Modern equation-based modeling languages provide this functionality in principle since the models are translated into executable code by separate model compilers. These compilers today generate code for standalone simulation using a fixed interface toward a number of numerical solvers. What is missing is a compiler that can generate customized code for various simulation environments, where the generated code interfaces with other models in the environment through the conventional solution of powerports. Each port holds both input and output variables such as force and velocity. A compiler architecture is proposed in this article. Also, an implementation for a subset of the Modelica language is demonstrated in the case of two widely different simulation environment targets. The model ports are adapted initially to the simulation environment characteristics in terms of the variables part of the ports, and an input-output causality is found for which the model can be solved and that suits the environment. The equation system is optimized, and information such as Jacobians, assignments, and more is generated in the XML format. Finally, code generators specific for each environment are employed that create the final executable code. © 2006 The Society for Modeling and Simulation International.

 The equation-based modeling language Modelica offers the possibility to extract a differential algebraic equation system (DAE). The DAE in turn can be used in numerical simulation, optimization, sensitivity analysis, diagnosis and more. For each of these categories, there exist software tools that all require slightly different input data, sometimes in symbolic form. Through examples, this paper briefly outlines a Modelica based format which can be used as input to the final code generation. This could yield a modular Modelica compiler in which the creation of diverse code generators is encouraged, which in turn widens the application area for Modelica. However, no formal definition of the format is presented here.. The paper also briefly addresses the issue of possible model causal adaptation needed at the equation level to make the model fit into target application with a causal usage context and how to automate the inclusion of these changes for seamless translation.

The paper presents a fluid power model library in the equation-based modelling language Modelica and shortly shows how the library can be used in simulation software such as Matlab. The library is built such that valves and actuators can be built by engineers rather than simulation specialists and so that it is possible to compile into executable code with as little effort as possible. 

Car parking has been, and still is, a growing problem, with increasing vehicle sizes in the luxury segment as well as sport-utility vehicles. This is especially true when bearing in mind the confined parking spaces in parking lots and cities. While damage during parking generally does not cause any injury to the passengers, it is costly and annoying. Park assist systems are by no means new on the market, since passive systems which provide longitudinal guidance using ultrasonic distance sensors have been available on the market for a number of years.

The system presented is a semi-automated approach to parallel parking problems, as they frequently occur in European and Asian cities. The challenge during the development of this system was to have as few components as possible added to a standard vehicle, seeking reuse of many of the already built-in functionalities. The result is a system that leaves the longitudinal control of the vehicle to the driver but automates the steering process, and even stops the vehicle when the final parking position is reached.

Mobile machines of today often contain hydraulic valve controlled actuator loads in an open loop circuit. For the purpose of saving energy, the constant pressure pumps have in the past often been replaced by load sensing pumps and valves. In mobile applications, they have significantly reduced the energy consumption. Stricter environmental demands and rapidly increased fuel cost require an even lower consumption. By analyzing a typical working cycle of a construction machine, the possibility of energy recovery has been identified. The analyse confirms the importance of minimizing the metering losses. In a load-sensing valve solution these losses arise as a result of the unequal drive pressure levels. By adopting a displacement controlled regenerative solution, a significantly higher level of efficiancy can be obtained.