scholarly journals The reduction of the reaction torque of a straight four-cylinder four-stroke engine

2010 ◽  
Vol 142 (3) ◽  
pp. 82-87
Author(s):  
Ryszard MOSAKOWSKI
Keyword(s):  
The State ◽  
Propulsion System ◽  
Design Parameters ◽  
Complete Elimination ◽  
Engine Operation ◽  
Vehicle Propulsion ◽  
The Impact ◽  
Reaction Torque ◽  
Stroke Engine ◽  
Selection Of

The paper presents both the exact and simplified relations on the course of the reaction torque of a single and multi-cylinder engine, which is transmitted to the vehicle frame or foundation. The formula for the distance between the balance shafts along the vertical axes ensuring a complete elimination of the impact of the forces of inertia on the course of the reaction torque in four-stroke four-cylinder engines is derived in the paper. The criteria for selecting the optimum value of the distance are also derived in the paper. The dependence of the optimum value of the distance on the state of the engine operation and design parameters of the vehicle propulsion system is indicated in the paper. The paper proposes the selection of the optimum shafts distance, for a given type of vehicle, in areas of the engine most frequently used operating states.

scholarly journals Impact of Cross-Tie Properties on the Modal Behavior of Cable Networks on Cable-Stayed Bridges

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Javaid Ahmad ◽  
Shaohong Cheng ◽  
Faouzi Ghrib
Keyword(s):  
Analytical Model ◽  
Design Parameters ◽  
Reference Base ◽  
Cable Network ◽  
Cable Networks ◽  
Modal Behavior ◽  
Stiffness And Damping ◽  
Main Cables ◽  
The Impact ◽  
Selection Of

Dynamic behaviour of cable networks is highly dependent on the installation location, stiffness, and damping of cross-ties. Thus, these are the important design parameters for a cable network. While the effects of the former two on the network response have been investigated to some extent in the past, the impact of cross-tie damping has rarely been addressed. To comprehend our knowledge of mechanics associated with cable networks, in the current study, an analytical model of a cable network will be proposed by taking into account both cross-tie stiffness and damping. In addition, the damping property of main cables in the network will also be considered in the formulation. This would allow exploring not only the effectiveness of a cross-tie design on enhancing the in-plane stiffness of a constituted cable network, but also its energy dissipation capacity. The proposed analytical model will be applied to networks with different configurations. The influence of cross-tie stiffness and damping on the modal response of various types of networks will be investigated by using the corresponding undamped rigid cross-tie network as a reference base. Results will provide valuable information on the selection of cross-tie properties to achieve more effective cable vibration control.

The Impact of Modelling Air Compressibility in the Selection of Optimal OWC Design Parameters in Site Specific Wave Conditions

2019 ◽  
Author(s):  
Irene Simonetti ◽  
Lorenzo Cappietti
Keyword(s):  
Fluid Dynamic ◽  
Experimental Tests ◽  
Design Parameters ◽  
Dynamic Simulations ◽  
Regression Approach ◽  
Wave Conditions ◽  
A Site ◽  
The Impact ◽  
Period Wave ◽  
Selection Of

Abstract The importance of properly modelling the effects of air compressibility in the selection of the optimal design parameters for an Oscillating Water Column wave energy converter is investigated. For this purpose, a wide dataset of capture width ratios, obtained from both experimental tests and Computational Fluid Dynamic simulations, is used to formulate an empirical model able to predict the performance of the device as a function of its basic design parameters (chamber width and draught, turbine damping) and of the wave conditions (wave period, wave height). A multiple non-linear regression approach is used to determine the model numerical coefficients. The data used to formulate the model include the effects of air compressibility. The impact of considering such effects on the selection of the optimal geometry of the device is evaluated and discussed by means of the model application for the optimization of a device to be installed in a site located in the Mediterranean Sea (in front of the coast of Tuscany, Italy).

Development of an Exhaust Manifold Design Optimization for Cylinder Scavenging and Turbocharger Performance

2010 ◽  
Author(s):  
Diana K. Grauer ◽  
Kirby S. Chapman
Keyword(s):  
Research Team ◽  
Nox Reduction ◽  
Design Guidelines ◽  
Design Parameters ◽  
Exhaust Manifold ◽  
Engine Operation ◽  
Operating Range ◽  
Pressure Pulses ◽  
Scavenging Efficiency ◽  
The Impact

This paper presents an investigation into the NOX reduction role played by the exhaust manifold of large-bore two stroke cycle engines by exploring the impact of the exhaust manifold design on turbocharger and engine operation. Exhaust manifold performance is defined as the ability of the exhaust manifold to: 1) optimize cylinder scavenging efficiency; and 2) minimize the pressure differential between the compressor discharge and the turbine inlet by exploiting the blow-down pressure pulses and minimizing the static pressure gradient along the exhaust manifold. Pressure pulses in the exhaust manifold have been identified as a plausible mechanism that hinders efficient cylinder scavenging and turbocharger operating range. While modifying the ports and manifold may not be cost effective, a complete understanding of and the ability to address the impact of these pressure waves on turbocharger performance and scavenging efficiency will lead to more reliable engine upgrade projects as the industry approaches the 0.5 g/bhp-hr engine. The research team chose “available energy,” or the amount of mechanical and thermal energy available to the turbocharger turbine for operation as the parameter for defining optimal exhaust manifold design parameters. This allowed the research team to: 1) investigate energy losses in the candidate Clark TLA-6 exhaust removal system on a component basis, and 2) translate the mitigation of these losses into expanded turbocharger operating range. The end point of the project was a set of exhaust manifold design guidelines aimed at maximizing turbocharger performance by way of the defined metrics, scavenging efficiency and waste-gate margin.

Propulsion System Considerations for the Subsonic V/STOL

1979 ◽  
Vol 101 (2) ◽  
pp. 228-232
Author(s):  
J. D. Cyrus ◽  
M. DeVillier ◽  
J. Kaminski
Keyword(s):  
Propulsion System ◽  
The Core ◽  
Lower Weight ◽  
Engine Version ◽  
The Cost ◽  
The Impact ◽  
Selection Of

A representative subsonic V/STOL aircraft operating on a single mission has been used as a baseline to investigate the impact of various propulsion system tradeoffs. After establishing a cycle for the propulsion system and estimating V/STOL related installation penalties, parametric engine-aircraft-mission studies have been conducted. These studies have established takeoff gross weight benefits of up to 13 percent that may be obtained by appropriate selection of the core engine sizing location. Studies of two, three and four engine versions of the configuration have shown that three engine and four engine aircraft may have 20 percent lower weight than a two engine version, but this arises at the cost of significantly reduced hot section life.

Analysis of vibrations for a vibrating jaw crusher when interacting with material

2021 ◽  
pp. 26-31
Author(s):  
A. E. Shokhin ◽  
G. Ya. Panovko ◽  
I. P. Lyan
Keyword(s):  
Vibration Mode ◽  
Excitation Frequency ◽  
Design Parameters ◽  
Operating Modes ◽  
Jaw Crusher ◽  
Stable Periodic ◽  
The Impact ◽  
Excitation Conditions ◽  
Main Operating ◽  
Selection Of

A model of a vibrating jaw crusher (VJC) with self-synchronizing unbalanced vibration exciters is considered with account of the impacts between the jaws and the material being processed. Numerical modeling is used to establish the influence of the initial gap between the jaws and the material and of the velocity recovery factor upon impact on the synchronization of vibration exciters rotation and jaw vibrations, on the excitation frequency ranges of stable periodic vibroimpact regimes, and on the impact velocities between the jaws. The analysis results indicate that a change in the conditions of contact between the jaws and the material being processed leads to a change in the frequency ranges of the stable antiphase synchronization of vibration exciters rotation, as well as in the excitation frequency ranges of steady single-period vibroimpact regimes for the motion of the system, considered as the main operating modes of the VJC. The impact-like nature of the interaction between the jaws and the material being processed suggests the possible multimodality of the system, which explains some of the effects observed in practice and manifested in changes in the periodicity of the vibroimpact regime and in the vibration mode of the jaws at a constant excitation frequency. Therefore, the vibroimpact-based model proposed for the VJC and its dynamics analysis results may be used to design and improve vibrating jaw crushers with the selection of reasonable design parameters and the most effective vibration excitation conditions. The work was carried out with the financial support of the RFBR, project No. 18-08-01491_a.

scholarly journals A method for selection of parameters of ship propulsion system fitted with compromise screw propeller

2007 ◽  
Vol 14 (4) ◽  
pp. 3-6 ◽  
Author(s):  
Jan Michalski
Keyword(s):  
Optimization Problems ◽  
Mathematical Optimization ◽  
Stage Structure ◽  
Propulsion System ◽  
Design Stage ◽  
Design Parameters ◽  
Inland Waterways ◽  
Ship Propulsion ◽  
Screw Propeller ◽  
Selection Of

A method for selection of parameters of ship propulsion system fitted with compromise screw propeller This paper concerns an algorithmic method for preliminary selection of parameters of ship propulsion system fitted with fixed screw propeller in the case when the ship's operation is associated with significant changes of waterway depth and width, hull resistance of the ship and its service speed. Mathematical model arguments of the considered design problem are main ship design parameters identified in the preliminary design stage. Structure of the formulated model complies with formal requirements for continuous- discrete mathematical optimization problems. The presented examples of application of the method concern an inland waterways ship fitted with compromise screw propeller optimized in the sense of minimization of fuel consumption for passing a given route distance within a given time. The elaborated method may be especially useful in designing such ships as: coasters, inland waterways ships, tugs, pushers, trawlers, mine sweepers, icebreakers etc.

scholarly journals Confidence Restoration Following Athletic Injury

2000 ◽  
Vol 14 (4) ◽  
pp. 372-390 ◽  
Author(s):  
T. Michelle Magyar ◽  
Joan L. Duda
Keyword(s):  
Social Support ◽  
Goal Orientations ◽  
Rehabilitation Program ◽  
The State ◽  
Athletic Injury ◽  
Intercollegiate Athletes ◽  
Injury Rehabilitation ◽  
The Social ◽  
The Impact ◽  
Selection Of

The impact of goal orientations, perceptions of social support, and sources of rehabilitation confidence on the process of confidence restoration from athletic injury was examined among 40 injured intercollegiate athletes (ages 18 to 22 years). Athletes completed the Task and Ego Orientation in Sport Questionnaire (TEOSQ; Duda & Nicholls, 1992), the Social Support Questionnaire (SSQ; Duda, Smart, & Tappe, 1989), and modified versions of the Sources of Sport Confidence Questionnaire (M-SSCQ; Vealey, Hayashi, Garner-Holman, & Giacobbi, 1998) and the State Sport Confidence Inventory (M-SSCI; Vealey, 1986) within the first two days of their rehabilitation program. The SSQ, M-SSCQ, and M-SSCI were completed during the midpoint of the rehabilitation and the day before returning to practice/competition. Results indicated that the tendency to emphasize task-involved goals in sport significantly predicted the selection of mastery and more self-referenced sources of confidence in rehabilitation. Athletes who perceived more social support specific to injury rehabilitation at the beginning of the rehabilitation program were more likely to rely on performance sources to build confidence.

Propulsion System Screening for Survivability and Effectiveness

1983 ◽  
Author(s):  
Hugh Montague
Keyword(s):  
System Design ◽  
Essential Element ◽  
Aircraft Design ◽  
Propulsion System ◽  
Weapon System ◽  
Early Screening ◽  
System Survivability ◽  
Design Options ◽  
The Impact ◽  
Selection Of

Selection of engines has been traditionally concerned with performance capability. Although performance is still an essential element in all future applications, recognition of operational realities has placed importance on system survivability and ultimate cost. In advanced military aircraft design, it is necessary and feasible to evaluate propulsion systems in a combat context that will discriminate according to the cost of performing the required mission. Methods are outlined which can be utilized during parametric studies to permit the screening of candidate design options, and identification of trends and design drivers. This approach provides the analyst with the ability to assess the impact of survivability and vulnerability characteristics upon the selection of the proper engine and propulsion system for a given mission task in terms of a cost related figure of merit. The importance of early consideration of these requirements in the weapon system design process has been dramtically illustrated by a recent study concerning propulsion survivability and weapon system design. The first preliminary aircraft design was found to be unacceptably susceptible to radar-seeking threat missiles. Utilizing the analytical results, a modest redesign to the aircraft reduced the combat cost by a factor of sixty. The results present informative phenomenology, while the methods illustrated show an approach that provides early screening, rapid optimization and ability to focus on the significant design factors.

scholarly journals - The factors affecting the evaluation and selection of hotels - An analytical study of a field a sample of tourists visiting the State of Djelfa - Algeria: العوامل التي تؤثر في تقييم واختيار الفنادق - دراسة ميدانية تحليلية لعينة من السياح الذين يقصدون ولاية الجلفة- الجزائر-

2020 ◽  
Vol 4 (3) ◽  
Author(s):  
Hiba Ali Toual, Siham Salem Mahamdi
Keyword(s):  
Interior Design ◽  
The State ◽  
Factors Affecting ◽  
The Social ◽  
Independent Variable ◽  
And Gender ◽  
Definition Of ◽  
The Impact ◽  
The Relationship ◽  
Selection Of

This research aims to study the impact of a range of factors on the evaluation and selection of hotels, for that we’ve conducted a study based on the descriptive analytical approach, where 100 questionnaires were distributed to a random sample of tourists visiting the state of Djelfa- Algeria. The study found that the evaluation and selection of the hotel within the sample members is influenced by the range of factors covered by the study (the purpose of the visit, the definition of value by the visitor, the social and economic factors, age and gender, race or religion). Depending on the correlation coefficient value (R 0.885), the relationship between the independent variable and the dependent variable was strong, and the independent variable explains 77.2%of the dependent variable. Finally, the study has presented a set of recommendations, which conclude in:- Renovation and development of the interior design of hotels;- Annual training programs including the hotel staff and this is to learn about new trends in the hotel’s industry.

Analysing Mussolini postcards

Modern Italy ◽  
2013 ◽  
Vol 18 (2) ◽  
pp. 141-156 ◽  
Author(s):  
Enrico Sturani
Keyword(s):  
Popular Culture ◽  
Small Proportion ◽  
The State ◽  
Totalitarian Regime ◽  
For Profit ◽  
Production Distribution ◽  
Fascist Regime ◽  
The Impact ◽  
Selection Of

During the Fascist regime millions of postcards circulated featuring Mussolini in many different guises and forms. This article reflects on their production, distribution and consumption and considers the extent to which they can be seen as part of the propaganda of a totalitarian regime. It also explores the meanings of the imagery of a selection of postcards. It argues that Mussolini postcards, despite their vast numbers, amounted in fact to only a small proportion of those circulating under the regime. Moreover, many of them were produced by private publishers for profit rather that Fascist organisations or the state. Therefore they cannot simply be considered as a manifestation of totalitarianism and must rather be conceived in large part as an effect of the impact of Mussolini on popular culture.

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