scholarly journals A Critical Review of Approaches to the Design of Floating-Liner Apparatus for Instantaneous Piston Assembly Friction Measurement

Lubricants ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 10
Author(s):  
Abdelrahman M. Youssef ◽  
Graham Calderbank ◽  
Ian Sherrington ◽  
Edward H. Smith ◽  
Homer Rahnejat
Keyword(s):  
Critical Review ◽  
Effective Pressure ◽  
Friction Measurement ◽  
Bench Tests ◽  
Main Design ◽  
Ic Engines ◽  
Friction Measurements ◽  
Design Challenges ◽  
Detailed Presentation ◽  
Piston Assembly

Several approaches have been developed to measure instantaneous friction between the piston assembly and cylinder in internal combustion (IC) engines, such as floating-liner, reciprocating liner, instantaneous mean effective pressure (IMEP), fixed sleeve, and (P-ω) method and tribological bench tests. However, the “floating-liner method” and the “(IMEP) method” are the most common methods used to measure instantaneous friction between the piston assembly and IC engines. This paper critically evaluates different approaches to the design of the “floating-liner”. The paper begins by discussing piston assembly frictional losses and their significance and then discuss the development of instantaneous piston-friction measurements. After that, it reviews the main design challenges in the floating-liner approach. “Methods of cylinder sealing” and “force balancing methods” are also reviewed. Design challenges associated with firing operation were presented. Floating-liner designs were classified into different categories with a detailed presentation of the features of each. The paper ends by presenting a range of broad recommendations for further work which would benefit future designs.

Progress and design challenges for high-spin molecules

2010 ◽  
Vol 83 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Martin T. Lemaire
Keyword(s):  
Free Radical ◽  
Metal Complexes ◽  
High Spin ◽  
Critical Review ◽  
Mixed Valence ◽  
Double Exchange ◽  
Stable Free Radical ◽  
The Past ◽  
Molecule Design ◽  
Design Challenges

In this short critical review, selected examples of current (within the past two years) synthetic efforts toward the construction of high-spin molecules are explored, including the use of metal complexes containing stable free radical ligands, lanthanide or actinide complexes, and other coordination clusters, or a completely different approach, taking advantage of non-Heisenberg exchange in fully delocalized mixed-valence complexes (spin-dependent delocalization, SDD, or double exchange). A description of reported work in this regard is followed by a brief general discussion that highlights what the future may hold for high-spin molecule design.

scholarly journals Construction of a Light Rail line to Wilanów

2016 ◽  
Vol 2016 (7) ◽  
pp. 9-16
Author(s):  
Grzegorz Madrjas
Keyword(s):  
Feasibility Studies ◽  
Light Rail ◽  
Historical Aspects ◽  
Main Design ◽  
Rail Line ◽  
Design Ideas ◽  
Design Challenges

The paper describes main design ideas for a project of a tramway connection between districts of Warsaw: Wola, Ochota, Mokotów and Wilanów. Historical aspects, main spatial documents as well as feasibility studies are also discussed. Moreover, key design challenges are presented which concern routing options and limitations of passing through special locations.

scholarly journals Determination of the optimal composition of mixed fuel based on the environmental performance of a diesel engine

2021 ◽  
Vol 1 (1) ◽  
pp. 14-22
Author(s):  
S.A. Plotnikov ◽  
◽  
Sh.V. Buzikov ◽  
I.S. Kozlov ◽  
◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Diesel Engine ◽  
Environmental Performance ◽  
Environmental Indicators ◽  
Effective Pressure ◽  
Bench Tests ◽  
Mixed Fuel ◽  
Unburned Hydrocarbons ◽  
Carbon Dioxide Co2

The use of rapeseed oil (RO) in tractor engines and other agricultural machinery in its pure form or a mixture of RO with diesel fuel (DF) imposes a number of limitations associated with some dif-ference in physical and chemical properties. Therefore, the most promising is the use of mixed fuel (MF) consisting of DF and RO. The purpose of these studies is to determine the optimal composi-tion of the MF, consisting of DF and RM by optimizing the approximated dependences of the envi-ronmental indicators of a diesel engine. To solve this problem, bench tests of the operation of the D-245.5S diesel engine (4ChN 11.0 / 12.5) were carried out. The following determined environmental performance indicators of a diesel engine are selected: soot (С), nitrogen oxides (NOx), unburned hydrocarbons (CxHy), carbon dioxide (CO2) and carbon monoxide (CO). The studies were carried out on various compositions of MF, consisting of 80% DF and 20% RO, 55% DF and 45% RO, 20% DF and 80% RO by weight, respectively. As a result of the bench tests, two load characteris-tics were obtained, the one at a speed of n = 1400 min-1 corresponding to the value of the maximum torque, and the second at a speed of n = 1800 min-1 corresponding to the value of the rated power, as well as the external speed characteristic of the D-245.5S tractor diesel engine (4ChN 11.0 / 12.5). The analysis of the obtained experimental data revealed the dependence of environmental indicators on the rotational speed of the diesel engine crankshaft, the average effective pressure and the addi-tion of RO in MF by weight. Using the least squares method, the approximated mathematical de-pendences of the ecological indicators of a diesel engine are determined. The analysis of the ob-tained dependencies showed that: the increase in the crankshaft speed n, the proportion of RO in MF and a decrease in the average effective pressure pe, leads to a decrease in soot С to 4.0%, nitro-gen oxides NOx to 100.0 ppm, unburned hydrocarbons CxHy to 1.0 ppm, carbon dioxide, CO2 up to 2%, and an increase in carbon monoxide CO up to 0.16%. As a result of solving the obtained system of equations for the approximated dependences of environmental indicators, the optimal addition of RO to MF of up to 35% by weight was determined.

Interconversion of Locked-Wheel and Continuous Friction Measurement Equipment (CFME) Friction Measurements

2018 ◽  
Vol 2672 (40) ◽  
pp. 452-462
Author(s):  
Silvia Barrantes Quiros ◽  
Gerardo W. Flintsch ◽  
Edgar de León Izeppi ◽  
Kevin K. McGhee
Keyword(s):  
Absolute Error ◽  
Test Facility ◽  
Coefficient Of Determination ◽  
Measurement Equipment ◽  
Friction Measurement ◽  
Force Coefficient ◽  
Wide Range ◽  
Friction Measurements ◽  
Reference Measurements ◽  
Pavement Friction

As transportation agencies are adopting proactive pavement friction management using continuous friction measurement equipment (CFME), the need for a method that allows interconversion between the traditional locked-wheel skid testers (LWSTs) becomes important to assure continuity with past practices. This paper evaluates several conversion methods based on the International Friction Index (IFI) approach and proposes an alternative method that allows predicting the measurements of the LWST using measurements with the Sideway-Force Coefficient Routine Investigatory Machine (SCRIM). The investigation is based on data collected using a SCRIM and two LWSTs on a controlled pavement test facility. The results suggest that a conversion based only on the speed adjustments (FR60) is the most effective method to predict the LWST measurements from SCRIM measurements. The coefficient of determination and average absolute error are comparable to those using the full IFI F60 formula but do not require static reference measurements. The study also showed that the three tested devices produced appropriate repeatability as computed using the limit of agreement at the three tested speeds and on a wide range of surfaces.

“Lost Available IMEP”: A Second-Law-Based Performance Parameter for IC Engines

2016 ◽  
Author(s):  
H. Mahabadipour ◽  
K. K. Srinivasan ◽  
S. R. Krishnan
Keyword(s):  
Natural Gas ◽  
Performance Parameter ◽  
Second Law ◽  
Dual Fuel ◽  
Effective Pressure ◽  
Closed Cycle ◽  
Indicated Mean Effective Pressure ◽  
Second Law Analysis ◽  
Ic Engines ◽  
Engine Size

The second law of thermodynamics is a powerful tool for investigating thermodynamic irreversibilities and to identify pathways for improving efficiencies of energy systems, including IC engines. In the present work, second law analysis is applied to quantify irreversibilities in diesel-ignited natural gas dual fuel low temperature combustion (LTC), which utilizes diesel to ignite natural gas to simultaneously reduce emissions of oxides of nitrogen and particulate matter. A previously validated multi zone thermodynamic model of dual fuel LTC was used as the basic framework to perform the second law analysis. The multi-zone model, which simulates closed cycle processes between intake valve closure (IVC) and exhaust valve opening (EVO), divides the cylinder contents into four main zones: (i) an unburned zone containing a premixed natural gas-air mixture, (ii) a pilot fuel zone (or “packets”) containing diesel vapor and entrained natural gas-air mixture, (iii) a flame zone, and (iv) a burned zone. By applying the second law systematically to each zone, the total entropy generated over the closed cycle (Sgen) and the lost available work (Wlost = T0*Sgen) were quantified. Subsequently, the lost available work was divided by the displaced volume to calculate a new engine performance parameter labeled “lost available indicated mean effective pressure” (LAIMEP). Proceeding analogously from the definition of indicated mean effective pressure (IMEP) as an engine-size-normalized measure of indicated work, the LAIMEP may be interpreted as an engine-size-normalized measure of available work that is lost due to thermodynamic irreversibilities. Since LAIMEP is independent of engine size, it can be used to compare thermodynamic irreversibilities between engines of various displaced volumes as well as between different engine combustion strategies. Two additional second-law-based parameters: fuel conversion irreversibility (FCI) as the ratio of Wlost to total fuel chemical energy input and normalized LAIMEP as the ratio of LAIMEP to IMEP, were also defined. Parametric studies were performed at different diesel injection timings (SOI ∼ 300–340 CAD), intake temperatures (Tin ∼ 50°–150°C), and intake boost pressures (Pin ∼ 1–2.4 bar) to characterize their impact on LAIMEP and FCI. It was determined that both LAIMEP and FCI increased with SOI advancement (from 340 to 300 CAD) and decreased with increasing Tin and Pin. These trends were explained using predicted combustion parameters, especially burned mass fraction and average in-cylinder temperature at EVO. While the present work focused on diesel-natural gas dual fuel LTC (as an example), the overall methodology adopted for the second law analysis as well as the conceptual definitions of LAIMEP, FCI, etc., are generally applicable to any IC engine operating on any combustion strategy (e.g., SI, CI, LTC, etc.).

Parsing in the Minimalist Program: On SOV Languages and Relativization

2008 ◽  
Vol 53 (2-3) ◽  
pp. 237-252
Author(s):  
Sandiway Fong
Keyword(s):  
Relative Clauses ◽  
Minimalist Program ◽  
Goal Theory ◽  
Main Design ◽  
Starting Point ◽  
Syntactic Representation ◽  
To Come ◽  
Design Challenges ◽  
Linguistic Basis

AbstractI examine computational issues in the processing of SOV languages in the probe-goal theory of the Minimalist Program. A theory that minimizes search, such as the probe-goal theory, provides a strong linguistic basis for the investigation of efficient parsing architecture. For parsing, two main design challenges are presented: (i) how to limit search while incrementally recovering structure from input without the benefit of a pre-determined lexical array, and (ii) how to come up with a system that not only correctly resolves parsing ambiguities, but does so with mechanisms that are architecturally justified. I take as the starting point an existing probe-goal parser with features that allow it to compute syntactic representation without recourse to derivation history search. I extend this parser to handle pre-nominal relative clauses of the sort found in SOV languages. I provide a unified computational account of facts on possessor (and non-possessor) relativization and processing preferences in Turkish, Japanese, and Korean.

Design of Hexapod Walking Robots

2015 ◽  
pp. 527-566 ◽  
Author(s):  
Franco Tedeschi ◽  
Giuseppe Carbone
Keyword(s):  
Control System ◽  
Design Procedure ◽  
Walking Robots ◽  
Technical Feasibility ◽  
Main Design ◽  
Walking Gait ◽  
System A ◽  
And Performance ◽  
And Control ◽  
Design Challenges

This chapter deals with hexapod walking robot design and operation. The first section gives a wide overview of the state-of-the-art on hexapod walking robots by referring both to early design solutions and to most recent achievements. Section two identifies the main design challenges that influence the technical feasibility and performance of these systems. In section three, a design procedure is proposed. In particular, the proposed design procedure takes into account mechanical structure, leg configuration, actuating and drive mechanisms, payload, motion conditions, walking gait, and control system. A case of study is carefully described as referring to previous experiences at LARM.

scholarly journals Influence of piston surface treatment on piston assembly friction in an eco-mileage vehicle engine

2021 ◽  
Author(s):  
Kohei Nakashima ◽  
Yosuke Uchiyama
Keyword(s):  
Surface Treatment ◽  
Fine Particle ◽  
Cylinder Liner ◽  
Friction Measurement ◽  
Ceramic Particles ◽  
Vehicle Engine ◽  
Treatment Standard ◽  
Engine Friction ◽  
Micro Dimple ◽  
Piston Assembly

This study investigated the effect on piston assembly friction after treating piston surfaces with a fine particle bombarding process, using a friction measurement apparatus with a floating cylinder liner, similar to an eco-mileage vehicle engine. Friction was measured in four conditions: (1) no treatment (standard piston in a commercially-available engine), (2) micro dimple treatment (45 μm ceramic particles were air-blasted onto the piston surface), (3) molybdenum disulfide (MoS2) shot treatment (1 μm MoS2 particles were air-blasted onto the piston surface), and (4) combination of the previous two micro dimple and MoS2 shot treatments (first 45 μm ceramic particles and then 1 μm MoS2 were air-blasted onto the piston surface). Results indicated that friction decreased in the following order: no treatment > micro dimple treatment > MoS2 shot treatment > combination of micro dimple and MoS2 shot treatments.

Field Investigation of Relationship between Pavement Surface Texture and Friction

2018 ◽  
Vol 2672 (40) ◽  
pp. 395-407 ◽  
Author(s):  
Sareh Kouchaki ◽  
Hossein Roshani ◽  
Jorge A. Prozzi ◽  
Natalia Zuniga Garcia ◽  
Joaquin Bernardo Hernandez
Keyword(s):  
Surface Texture ◽  
Laser Scanner ◽  
Field Investigation ◽  
Horizontal Resolution ◽  
Strong Positive Correlation ◽  
Friction Measurement ◽  
Pavement Surface ◽  
Circular Track ◽  
Friction Measurements ◽  
The Right

Proper tire–pavement interaction is essential for the safety of motorists. Pavement surface texture is a major contributing factor to tire–pavement friction. This study performed a series of statistical analyses of field-measured friction and texture data to find the texture–friction correlation. Three test sections with different pavement types were selected within the state of Texas. Data were collected at three locations in the right wheel path and three locations in the center of the lane for each test section. To measure the texture data, the researchers used the circular track meter (CTM) and a prototype measurement device developed in-house and consisting of a line laser scanner (LLS). Friction measurements were obtained with the dynamic friction tester (DFT) and Grip-Tester. The mean profile depth (MPD) was calculated by using the measured texture data. The relationship between the MPD values and the friction numbers obtained from the Grip-Tester and DFT was investigated at speeds of 50 and 70 km/h (31.1 and 43.5 mph). The repeatability and reliability of both the developed LLS prototype and the Grip-Tester were also evaluated, as well as the effect of test speed on friction measurement. The results indicated a strong positive correlation between the texture and friction data. In addition, the developed LLS prototype was able to scan the pavement surface texture more reliably and precisely than the CTM in terms of vertical and horizontal resolution. The Grip-Tester showed promising results compared with the DFT with regards to the friction measurement.

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