On the addition of degrees of freedom to force-balanced linkages

The design of shaking-force balanced linkages can be approached by deriving these linkages from balanced linkage architectures. When desired, a possible step is to add degrees-of-freedom (dof), for instance by substituting a link with a n-dof equivalent linkage for which the balanced design of the other links is not affected. This paper shows how the coupler link of a shaking-force balanced 4R four-bar linkage, applied as a 5R five-bar linkage, can be substituted with an equivalent 2-dof pantograph

Mass equivalent triads

In this paper it is shown how a general 3-DoF triad can be designed mass equivalent to a general (1-DoF) link element. This is useful in the synthesis of shaking force balanced and statically balanced mechanisms, for instance to add or remove a number of DoFs of a balanced mechanism maintaining its balance. Also it can be used as a simple approach for synthesis of complex balanced mechanisms. To obtain the parameters for mass equivalence, a mass equivalent model with real and virtual equivalent masses is used. The characteristics of this model are explained and the properties of a mass equivalent triad are shown. Subsequently the parameters of a mass equivalent triad are derived with the method of rotations about the principal points (RAPP) and application examples are il-lustrated and discussed

Signal Transduction Involved in Cell Volume Regulation

1.fammalian cells are surrounded by a selective permeable plasma membrane that allmvs the interior of the cell to differ in composition from the surrounding solution. The plasma membrane is formed by a bilayer of (phospho-) lipids and contains many different proteins. Hydrophobic molecules such as hydrocarbons, carbon dioxide and oxygen, rapidly dissohTc into the membrane and can cross it by diffusion. Other small molecules that are polar but uncharged, for example \\vater and ethanol, can also pass the membrane by simple diffusion. In contrast, the membrane is selectively permeable for specific ions and polar molecules that can only croSs the membrane barrier with the aid of specific membrane-spanning transport proteins. Some of these proteins form hydrophilic channels through \\"vhich specific molecules diffuse dmvn their concentration gradient (passive transport). Other transport proteins use energy (direct or indirect) to pump molecules against their concentration gradient into or out of the cell (active transport)

Tengsl bandvefs og verkja

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadÍ þessari grein er reynt að varpa ljósi á þátt bandvefs (fascia) sem uppsprettu útlægrar skyntruflunar (nociception) í langvinnum verkjavanda. Þessa nálgun hefur verið stuðst við hjá Erasmus Medisch Centrum í Rotterdam og út frá henni þróuð endurhæfingaraðferð þar sem bandvefurinn er tekinn með inn í myndina í meðferð langvinnra verkja. Þetta er heildræn nálgun. Hún beinist að meðhöndlun útlægrar verkjauppsprettu og endurheimt jafnvægs í vöðva-bandvefskerfinu með sérhæfðum „manual“ meðferðaraðferðum og æfingum. Greinin fjallar um þessa nálgun og útskýrir nánar þrjár mismunandi útlægar uppsprettur skyntruflunar sem geta valdið verkjum þ.e. kveikjupunkta (triggerpoints), sjúkleika í bandvefshimnum (fasciapathology) og truflun á hreyfanleika taugavefs (neuropapathodynamics

Double pendulum balanced by counter-rotary counter-masses as useful element for synthesis of dynamically balanced mechanisms

Complete dynamic balancing principles still cannot avoid a substantial increase of mass and inertia. In addition, the conditions for dynamic balance and the inertia equations can be complicated to derive. This article shows how a double pendulum can be fully dynamically balanced by using counter-rotary counter-masses (CRCMs) for reduced additional mass and inertia. New CRCM-configurations were derived that have a low inertia, a single CRCM or have all CRCMs near the base. This article also shows how a CRCM-balanced double pendulum can be used as building element in the synthesis of balanced mechanisms for which the balancing conditions and inertia equations can be written down quickly. For constrained mechanisms the procedure is to first write down the known balancing conditions and inertia equations for the balanced double pendula and subsequently substitute the kinematic relations

Synthesis method for linkages with conter of mass at invariant link point-Pantograph based mechnisms

This paper deals with the synthesis of the motion of the center of mass (CoM) of linkages as being a stationary or invariant point at one of its links. This is of importance for the design of inherently shaking force balanced mechanisms, static balancing, and other branches of mechanical synthesis. For this purpose Fischer's mechanism is investigated as being a composition of pantographs. It can be shown that linkages that are composed of pantographs and of which all links have an arbitrary CoM can be inherently balanced for which Fischer's method is a useful tool. To calculate the principal dimensions for which linkages have their CoM at an invariant link point, an approach based on linear momentum is proposed. With this approach it is possible to investigate each degree-of-freedom individually. Equivalent Linear Momentum Systems are proposed to facilitate the calculations in order to use different convenient reference frames. The method is applied to planar linkages with revolute joints, however it also applies to linkages with other types of joints. As a practical example a shaking force and shaking moment balanced 2-DoF grasper mechanism is derived. -------------------------------------------------------------------------------