Osteoarthritis and Falls: Is there a Link?

Osteoarthritis, a widespread joint disease, commonly results in considerable pain and functional disability, especially among older adults. At the same time, falls and fall injuries, also common among the older population, may not only contribute to the onset of osteoarthritis, but once established, to falls that lead to fractures and disability in their own right. But what does the research show specifically? Objective This report aimed to examine what is known about the interrelationship between falls and osteoarthritis and the implications that can be drawn from this information. Methods Using the PUBMED data base, studies describing an association between osteoarthritis and falls were sought. Those fulfilling the eligibility criteria were reviewed and summarized in narrative form. Results Consistent support for an osteoarthritis-falls associated linkage is limited and not as robust as one would predict. Whether the observed associations between these health determinants are a cause of osteoarthritis, a consequence or both, or simply spurious findings is hard to decipher. Conclusion More numerous and carefully designed research to examine this issue is warranted and may be extremely helpful in preventing, as well as ameliorating a high degree of excess disability and associated fiscal costs due to both falls as well as osteoarthritis among the elderly.

Derivation of contracted graphs with ternary/quaternary links for type synthesis of parallel mechanisms by characteristic strings

SUMMARYThis paper focuses on the derivation of valid contracted graphs (CGs) with ternary links T and quaternary links Q using characteristic strings for type synthesis of parallel mechanisms. First, some concepts on the associated linkage, the CGs, and characteristic strings are explained, and the numbers of vertices and edges for constructing CGs with T and Q are solved. Second, the relative criteria are determined for representing CGs with T and Q and identifying their isomorphism using characteristic strings. Third, some simple CGs with T and Q are represented by the characteristic strings and their isomorphic/invalid CGs are identified. Finally, many complex, valid CGs with T and Q are derived by characteristic strings.

Analysis and Determination of Associated Linkage, Redundant Constraint, and Degree of Freedom of Closed Mechanisms With Redundant Constraints and/or Passive Degree of Freedom

The relations among the associated linkages (ALs), the redundant constraints, the passive degree of freedom (DoF), and the degree of freedom are studied systematically for the type synthesis of the closed mechanisms in this paper. First, the kinematic pairs with multidegree of freedoms are formed by combination of the basic joints with single degree of freedom in series, and the formulae are derived for the calculation of the degree of freedoms of the associated linkages, the number of the basic joints, and the valid numbers of the basic links in the associated linkages. Second, many different associated linkages and the number of basic links are derived, and the relations among the associated linkages, the redundant constraints, the passive degree of freedom, and the degree of freedoms of the closed mechanisms are analyzed. Third, some topology graphs are derived and the relative closed mechanisms with the redundant constraints and the passive degree of freedom are synthesized. Finally, the redundant constraints and the degree of freedoms of the closed mechanisms are determined.

Inlet Guide Vane Failure: Aero-Mechanical and System Control Interaction Effect

The APU, a gas turbine engine is designed to provide the aircraft with electrical power and pneumatic air both on the ground and in-flight conditions. The variable inlet guide vane (VIGV) system is used to regulate the air flow to the load compressor. The vane motions are controlled by an actuator and associated linkage. Common failure mechanisms of the VIGV such as cracking, corrosion of vanes, have been reported. This paper discusses a particular mode of failure which involves the aero-mechanical and control feedback interaction. The failure phenomenon is characterized by sector and ring gear tooth non-uniform wear, jamming of sector gears, actuator resonance, actuator fluid contamination and subsequent engine shutdown. Solution to failure mode is also discussed.

Synthesis and Analysis of Stroke-Increasing and Force-Balancing Mechanisms for Rod Pumping Units

This paper introduces a creative synthesis and analysis of stroke-increasing and force-balancing mechanisms for rod oil pumping units by using the systematic linkage technique. The corresponding relations between the kinematic components in mechanisms and the link element in associated linkage are determined. Four acceptable associated linkages are used to create eight new types of mechanisms for rod oil pumping units. Formulas are derived for calculating stroke, counterweight mass, and driving force. For each synthesized mechanism, an analysis of properties, working loads, and strokes is conducted. Finally, a better mechanism for the rod oil pumping units is presented.

Creative Design of Epicyclic Gear Trains Using Number Synthesis

The following paper applies the theory of number synthesis to the creative design of epicyclic gear trains. First, the associated linkage of an existing epicyclic gear train is derived as an initial step of analysis. Next, the requirements for an acceptable associated linkage are established. Finally, epicyclic gear trains are derived by number synthesis from acceptable associated linkages up to and including the degree of complexity of eight links.