Controlling Prime Movers

2020 ◽  
pp. 271-281
Author(s):  
Neil Petchers
Keyword(s):  
Prime Movers

scholarly journals Is the Occurrence of the Sticking Region in Maximum Smith Machine Squats the Result of Diminishing Potentiation and Co-Contraction of the Prime Movers among Recreationally Resistance Trained Males?

2021 ◽  
Vol 18 (3) ◽  
pp. 1366
Author(s):  
Roland van den Tillaar ◽  
Eirik Lindset Kristiansen ◽  
Stian Larsen
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Gluteus Maximus ◽  
Knee Extensors ◽  
Force Output ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Prime Movers ◽  
Almost All ◽  
Height Data

This study compared the kinetics, barbell, and joint kinematics and muscle activation patterns between a one-repetition maximum (1-RM) Smith machine squat and isometric squats performed at 10 different heights from the lowest barbell height. The aim was to investigate if force output is lowest in the sticking region, indicating that this is a poor biomechanical region. Twelve resistance trained males (age: 22 ± 5 years, mass: 83.5 ± 39 kg, height: 1.81 ± 0.20 m) were tested. A repeated two-way analysis of variance showed that Force output decreased in the sticking region for the 1-RM trial, while for the isometric trials, force output was lowest between 0–15 cm from the lowest barbell height, data that support the sticking region is a poor biomechanical region. Almost all muscles showed higher activity at 1-RM compared with isometric attempts (p < 0.05). The quadriceps activity decreased, and the gluteus maximus and shank muscle activity increased with increasing height (p ≤ 0.024). Moreover, the vastus muscles decreased only for the 1-RM trial while remaining stable at the same positions in the isometric trials (p = 0.04), indicating that potentiation occurs. Our findings suggest that a co-contraction between the hip and knee extensors, together with potentiation from the vastus muscles during ascent, creates a poor biomechanical region for force output, and thereby the sticking region among recreationally resistance trained males during 1-RM Smith machine squats.

scholarly journals Elite associations and the politics of belonging in Cameroon

Africa ◽  
1998 ◽  
Vol 68 (3) ◽  
pp. 320-337 ◽  
Author(s):  
Francis Nyamnjoh ◽  
Michael Rowlands
Keyword(s):  
Political Parties ◽  
Local Level ◽  
State Control ◽  
National Politics ◽  
Authoritarian State ◽  
Prime Movers ◽  
The Creation ◽  
Formal Distinction

The development of elite associations has been a consequence of the growth of multi-partyism and the weakening of authoritarian state control in Cameroon in the 1990s. The attachment of electoral votes and rights of citizenship to belonging to ethnicised regions has encouraged the formal distinction between ‘natives’ and ‘strangers’ in the creation of a politics of belonging. The article argues that this development has also led to the replacement of political parties at the local level by ethnicised elite associations as prime movers in regional and national politics.

Performance analysis of a combined cooling, heating, and power system driven by a waste biomass fired Stirling engine

2010 ◽  
Vol 225 (2) ◽  
pp. 420-428 ◽  
Author(s):  
J Harrod ◽  
P J Mago
Keyword(s):  
Energy Consumption ◽  
Natural Gas ◽  
Wood Chip ◽  
Primary Energy ◽  
Stirling Engine ◽  
Primary Energy Consumption ◽  
Operational Cost ◽  
Excess Production ◽  
Prime Movers ◽  
Combined Cooling

Due to the soaring costs and demand of energy in recent years, combined cooling, heating, and power (CCHP) systems have arisen as an alternative to conventional power generation based on their potential to provide reductions in cost, primary energy consumption, and emissions. However, the application of these systems is commonly limited to internal combustion engine prime movers that use natural gas as the primary fuel source. Investigation of more efficient prime movers and renewable fuel applications is an integral part of improving CCHP technology. Therefore, the objective of this study is to analyse the performance of a CCHP system driven by a biomass fired Stirling engine. The study is carried out by considering an hour-by-hour CCHP simulation for a small office building located in Atlanta, Georgia. The hourly thermal and electrical demands for the building were obtained using the EnergyPlus software. Results for burning waste wood chip biomass are compared to results obtained burning natural gas to illustrate the effects of fuel choice and prime mover power output on the overall CCHP system performance. Based on the specified utility rates and including excess production buyback, the results suggest that fuel prices of less than $23/MWh must be maintained for savings in cost compared to the conventional case. In addition, the performance of the CCHP system using the Stirling engine is compared with the conventional system performance. This comparison is based on operational cost and primary energy consumption. When electricity can be sold back to the grid, results indicate that a wood chip fired system yields a potential cost savings of up to 50 per cent and a 20 per cent increase in primary energy consumption as compared with the conventional system. On the other hand, a natural gas fired system is shown to be ineffective for cost and primary energy consumption savings with increases of up to 85 per cent and 24 per cent compared to the conventional case, respectively. The variations in the operational cost and primary energy consumption are also shown to be sensitive to the electricity excess production and buyback rate.

scholarly journals Control System for and Sea Operation Experience With CODOG-Powered Frigates

1967 ◽  
Author(s):  
Stig Olof Svensson
Keyword(s):  
United States ◽  
Control System ◽  
The United States ◽  
Reduction Gear ◽  
Operational Experience ◽  
Jet Engine ◽  
Power Turbine ◽  
Twin Screw ◽  
Prime Movers ◽  
Safety Systems

The Royal Danish Navy frigate Peder Skram successfully passed her sea trials on March 15–19, 1966, and has been in operation for about nine months, with an accumulated gas turbine operation of 490 hr at the end of December 1966. The frigate has twin-screw CODOG propulsion machinery consisting of a 22,000-shp jet-engine-fed power turbine and a 2400-shp two-stroke diesel engine. These two alternative prime movers drive the propeller shafts with controllable-pitch propellers through a common reduction gear including freewheeling clutches. The control system is described, embracing the governor system, the maneuvering system, and the instrumentation and safety systems. Operational experience at sea, including parts of the trials, is described, as well as experience gained by the Royal Danish Navy, including the voyage made by the frigate to the United States in October–December 1966.

Prime movers of noisy gene expression

2005 ◽  
Vol 37 (9) ◽  
pp. 925-926 ◽  
Author(s):  
Johan Paulsson
Keyword(s):  
Gene Expression ◽  
Prime Movers

scholarly journals What caused the Viking Age?

Antiquity ◽  
2008 ◽  
Vol 82 (317) ◽  
pp. 671-685 ◽  
Author(s):  
James H. Barrett
Keyword(s):  
Viking Age ◽  
Young Males ◽  
Prime Movers

This paper addresses the cause of the Viking episode in the approved Viking manner – head-on, reviewing and dismissing technical, environmental, demographic, economic, political and ideological prime movers. The author develops the theory that a bulge of young males in Scandinavia set out to get treasure to underpin their chances of marriage and a separate domicile.

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